Semiconductor device and method for manufacturing the same

ABSTRACT

A method of manufacturing semiconductor device which comprises the steps of forming an insulating film on an Si substrate provided with a wiring layer, forming a contact hole connected to the wiring layer and a wiring groove in the insulating film, filling the contact hole with an Si film, successively forming an Al film and a Ti film all over the substrate, performing a heat treatment thereby to substitute the Al film for the Ti film, and to allow the Si film to be absorbed by the Ti film, whereby filling the contact hole and wiring groove with the Al film, and removing a Ti/Ti silicide which is consisting of Ti silicide formed through the absorption of the Si film by the Ti film and a superfluous Ti, whereby filling the contact hole with an Al plug and filling the wiring groove with an Al wiring.

This is a division of application Ser. No. 08/997,328, filed Dec. 23,1997 now U.S. Pat. No. 6,071,810, all of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

This invention relates to a semiconductor device having a structureprovided with contact holes and wiring grooves in an insulating film,and a method for manufacturing such a semiconductor device.

At present, a wiring comprising Al as a main constituent material isemployed in a semiconductor device. In particular, the wiring mostpopularly employed is manufactured by a process wherein a barrier filmfor inhibiting the Al film from reacting with an underlying layer isformed under an Al film, or a antireflection film for inhibiting theirregular reflection of light at the occasion of lithography is formedon an Al film, and then these laminated films involving the Al film thusdeposited are etched by means of RIE. Further, with an increase inintegration density of LSI, the wiring is now demanded to be formed intoa multi-layer wiring structure, thus necessitating a development of aplug-forming technique for making a connection between an upper wiringand a lower wiring.

On the other hand, with an increase in integration density ofsemiconductor devices, the wiring becomes increasingly fine, resultingin an decrease in cross-sectional area of the wiring and hence in anincrease in wire resistance. Moreover, the distance between each wiringsbecomes narrower, resulting in an increase in inter-wiring capacity.

Such increases in wire resistance and in inter-wiring capacity lead toan RC delay, thus hindering the operation of LSI. With an increase infineness of LSI, a multi-layer wiring is becoming more important as afactor for determining the operation speed of LSI. Therefore, thelowering in resistance of wiring as well as the lowering of dielectricconstant of interlayer insulating film are now urgently desired.

As one of the conventional plug-forming techniques, W (tungsten)-CVDtechnique is known to be excellent in step coverage. FIG. 1A shows across-sectional view of the conventional multi-layer wiring structurewhich has been formed by making use of the W-CVD. technique. In FIG. 1A,the reference numeral 81 denotes an interlayer insulting film, 82denotes a W plug and 83 denotes an Al wiring.

This W-CVD technique can be classified into two kinds, i.e. “blanketdeposition” and “selective deposition”. The “blanket deposition” is amethod wherein a W film is deposited all over a substrate including theinner surface of contact holes. On the other hand, the “selectivedeposition” is a method wherein a W film is deposited selectively onlyon the bottom surface of contact holes.

Both methods are performed under a thermal condition which is differentfrom each other. In the case of the “selective deposition”, the interiorof the contact holes can be filled with a W film in a single step.Whereas, in the case of the “blanket deposition”, an etch-back step or aCMP step is required as a post treatment for removing part of W filmwhich has been deposited outside the contact holes.

The W plug formed by making use of the aforementioned W-CVD technique isaccompanied with problems that it is high in resistance and poor in EM(electromigration) resistance.

The EM is a phenomenon where Al atoms in an Al wiring are caused to movedue to the collision thereof with electrons as an electric current ispassed through the Al wiring. W is a material which is more resistive toEM as compared with Al. When an upper Al wiring and a lower Al wiringare connected with each other through a W plug, an accumulation of Alatoms takes place at the upstream side of the flow of Al atoms while adepletion of Al atoms takes place at the downstream side.

The accumulation of Al or depletion of Al of this kind may give rise tothe generation of hillocks or voids, thus leading to a short circuitbetween wirings or a disconnection of wiring.

Further, in the case of the “blanket deposition”, part of W film whichhas been deposited outside the. contact holes is required to be removed,thus leading to an increase in number of manufacturing step. On theother hand, in the case of the “selective deposition” where a step ofremoving W film deposited outside the contact holes is not required, theselectivity of deposition is frequently deteriorated at present so thata step of RIE etch-back is also required subsequently.

As an alternative plug-forming technique, an Al reflow technique is alsoknown wherein a plug is formed by making use of Al which is lower inresistance than W. This method is featured in that it takes advantage ofthe fluidity through the surface diffusion of an Al film. This method isadvantageous in that the interior of the contact hole can be filled withAl by simply heating a substrate, thus making it possible to decreasethe number of the manufacturing step.

As a result of extensive studies, an underlying layer made for instanceof Ti (titanium) which is excellent in wettability in relative to Al isfrequently employed in the deposition of Al film. Furthermore, atwo-step reflow method, wherein Al is sputtered at first without heatingand then Al is sputtered again under a heated condition, is increasinglyemployed at present, since it is possible with this method to lower thefluidization temperature and to fill even a contact hole of high aspectratio (A.R.) (aspect ratio=depth of contact hole/pore diameter ofcontact hole).

Additionally, there have been various proposals wherein a reflowtechnique is combined with a sputtering technique of high directivity,such as a low pressure-long distance sputtering, a collimationsputtering and an HDP (high density plasma) sputtering.

On the other hand, there is a problem in the aforementioned Al reflowtechnique that it is very difficult with this method to effectively filla contact hole of high A.R. with Al. Since the Al reflow technique isbased on sputtering, it is inherently poor in step coverage.

Thus, the film thickness of Al becomes relatively thin at the bottomportion of contact hole, and the Al may be agglomerated when it isheated for fluidization, generating voids in the Al film buried in thecontact hole. For the purpose of overcoming this problem, a materialsuch as Ti which is excellent in wettability to Al is employed as anunderlying film as mentioned above, whereby preventing the agglomerationof Al.

However, when an underlying film is formed by a sputtering of Ti, anover-hang may be caused to develop at the opening portion of the contacthole, and the surface of Ti thus formed may become rugged. This ruggedsurface can be ascribed to the crystal face dependency of the crystalgrowth of Ti. The overhanging of Ti as well as the rugged surface of Tiprevents not only the adhesion of Al but also the reflow property of Al.Moreover, even if a directional sputtering of Ti is employed, it isalmost impossible to deposit a sufficiently thick Al film on the sidewall of contact hole according to the current technique.

Further, since Ti is reactive to Al, an Al₃Ti film is formed on thebottom of contact hole, and this Al₃Ti film may become a cause fordeteriorating the EM resistance of the Al plug as in the case of the Wplug.

The application of the Al reflow technique to a damascene structure or adual damascene structure is recently studied. FIG. 1B illustrates across-sectional view of the conventional dual damascene multi-layerwiring structure which has been formed by making use of the Al reflowtechnique. In FIG. 1B, the reference numeral 84 denotes a Ti/TiNlaminate film, 82 and 83 denotes an Al₃Ti film.

This dual damascene structure (DD structure) can be obtained by aprocess wherein contact holes and wiring grooves are formed in advancein an insulating film, and, after the interiors of these contact holesand wiring grooves are concurrently filled with Al film in a singlestep, any excessive externally exposed Al film is removed by means ofCMP (chemical mechanical polishing), whereby simultaneously forming Alwirings and Al plugs. It is possible, according to this dual damascenestructure, to simplify the manufacturing process and to save themanufacturing cost.

However, when a Ti film is employed as an underlying film and the Al—DDstructure is formed by making use of the Al reflow technique, the Al₃Tifilm may be formed also on the inner surface of the wiring grooves,since the wiring grooves are disposed at the upper portion of thecontact hole. Since Al₃Ti is high in electric resistance, the formationof Al₃Ti within the wiring may invite a reduction of the effectivevolume of the Al film and an increase in wire resistance. This problembecomes more serious as the width of wiring becomes increasingly narrow.

As explained above, there have been proposed various kinds ofplug-forming technique for filling a contact hole of high aspect ratiowith a conductive material. Among them, the Al reflow technique isdirected to the formation of a dual damascene structure. However, whenthe dual damascene structure is formed by making use of the Al reflowtechnique, Al₃Ti is caused to be formed due to a Ti/TiN laminate film tobe employed as an underlying film, thus giving rise to the problem of anincrease in wire resistance.

Aside from the aforementioned conventional-methods, a method of coveringa step portion (overhang portion) through a substitution between an Sifilm and an Al film has been proposed (Japanese Patent UnexaminedPublication S/60-46024).

This method is known to be excellent in step coverage and can beperformed by making use of the Si-CVD technique which has been employedin the manufacture of an LSI. Namely, according to this method, theoverhang portion is covered in advance with an Si film, an Al film isthen deposited on the Si film by means of sputtering, and the resultantlayers are heat-treated thereby substituting the Al film for the Sifilm.

According to this method, it is possible to perform the covering of anoverhang portion with an Al film, which could not be realized if only asputtering method is employed, or to perform the filling of a contacthole of high aspect ratio with an Al film.

However, if the quantity of Si diffused into the Al film exceeds overthe solid solution limit (the extent of solid solution) thereof in thismethod, an Si nodule (precipitation) may be formed at another location.If this Si nodule is formed within a wiring, it may become a cause forincreasing the electric resistance of the wiring, and if this Si noduleis formed between wirings, it may become a cause for a short circuitbetween the wirings.

For the purpose of minimizing the development of Si nodule, there hasbeen proposed a method wherein a Ti film is formed on an Al film, andthen the Si diffused into the Al film is allowed to be trapped by makinguse of the Ti film (Japanese Patent Unexamined Publication S/63-70455).

According to this method, since the Si in the Al film can be absorbed bythe Ti film, it is possible to suppress an increase in resistance of anAl—Si alloy wiring due to the Si nodule that may be generated at thebottom of contact hole during a heat treatment.

This method however is accompanied with a problem that since Ti iscontained in the wiring, a high resistant Al₃Ti is formed during heattreatment as in the case of the aforementioned reflow, so that thevolume of Al in relative to the volume of wiring is substantiallydecreased, thus increasing the wire resistance. This problem of increasein wire resistance becomes more serious as the wiring becomes higher inintegration and in fineness.

There is also proposed a method (Japanese Patent Unexamined PublicationH/2-199838) which is substantially a combination of the method disclosedin Japanese Patent Unexamined Publication S/60-46024 and the methoddisclosed in Japanese Patent Unexamined Publication S/63-70455.

According to this method, the interior of contact hole is filled inadvance with an Si film by making use of the Si-CVD technique, and thenan Al film is substituted for the Si film, whereby making it possible tocarry out the filling of a contact hole of high aspect ratio, anyexcessive Si film being absorbed by making use of a Ti film.

According to this method, it is possible to fill a contact hole of highaspect ratio with an Al film. The Al film is subsequently worked bymeans of RIE to form an Al wiring.

However, this method is accompanied with the following problems. Namely,the Al film to be obtained according to this method contains a productof high resistance such as Al₃Ti, which may be formed through a reactionbetween Ti silicide to be formed through an absorption of the Al film bythe Ti film and the Al film, or through a reaction between an excessiveTi film which has not been served for the absorption of the Si film andthe Al film.

Therefore, when the Al film containing a product of such a highresistance is worked by means of RIE to form an Al wiring, an Al wiring83 containing a high resistance product 87 on its upper surface as.shown in FIG. 2A, or an Al wiring 83 containing a high resistanceproduct 87 on its upper surface and side walls as shown in FIG. 2B wouldbe obtained.

The Al wiring 83 containing such a high resistance product 87 is toohigh in resistance to use it as a fine wiring. The reference numeral 86shown in these FIGS. 2A and 2 B denotes a first wiring.

BRIEF SUMMARY OF THE INVENTION

This invention has been accomplished under the aforementionedcircumstances, and the objects of-this invention is to provide asemiconductor device having a contact structure of high reliability thatis formed in an insulating film provided with contact holes and wiringgrooves.

Another object of this invention is to provide a method of manufacturinga semiconductor device having a contact structure of high reliabilitythat is formed in an insulating film provided with contact holes andwiring grooves.

The present inventor has at first found but a method of manufacturing anAl damascene structure or an Al dual damascene structure, which isfeatured in that an Al film is substituted for an Si film at first, anysuperfluous portion of the Si film is allowed to be absorbed by a Tifilm during or after the substitution, and reaction products which arehigh in resistance and formed between the Al film and Ti film or betweenthe Ti film and Si film are removed by means of the CMP method. Asmatter of fact, it has been confirmed by the present inventor that thereaction products causing an increase in wire resistance can be easilyremoved, thus making it possible with this method to lower theresistance of the wiring.

It has been also found out by the present inventor that theaforementioned method is accompanied with various problems as explainedbelow. Namely, the quantity of Si to be substituted becomes excessivedepending on the layout of pattern at the occasion of carrying out thesubstitution between the Si film and the Al film after the interiors ofthe wiring groove and contact hole are filled with the Si film.

As a result, a long period of time is required for the substitution,thus lowering the throughput. Furthermore, a Si nodule tends to bepartially developed, thus increasing the electric resistance of wiringif the nodule is formed on the wiring. The generation of the Al nodulemay become a cause for generating a flaw in the subsequent CMP process.Namely, it has been found that the aforementioned method is accompaniedwith various problems to be solved before it is put into an actual use.

This invention has been accomplished with a view to solve theaforementioned problems.

[1] Namely, this invention provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film (a film to be substituted) so as toincompletely fill interiors of the contact hole and the wiring groove,but at least partially filling the interior of contact hole with thesubstitutive film;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

It has been also found as a result of studies made by the presentinventor that if the quantity of Ti is too large, a void is more likelyto be formed in the Al film. This phenomenon can be ascribed to the factthat when the Si filled in the wiring groove or in the contact hole isabsorbed by the upper Ti layer so as to be substituted by Al, a reactionlayer formed as a result of reaction of Si with Ti gives a stress to theAl film.

Namely, an AlTi compound layer is formed at the interface of Al/Ti inthe heat treatment for effecting the substitution between Si and Al, andat the same time, the Si diffused through the Al film is caused to reactwith Ti to form a TiSi compound layer, thus giving rise to thegeneration of void in the Al film due to stress exerted by the AlTicompound layer and the TiSi compound layer. In particular, the stressgradient that will be given by the AlTi compound to the Al film isrelatively large, so that some measures are required to suppress theformation of the AlTi compound.

The dual damascene structure comprises an Al wiring in the lower layerthereof, so that when the Si filled in the upper wiring groove andcontact hole is substituted by Al, the void may be generated in thislower Al wiring layer too. When the lower wiring is not formed with anAl wiring but with W, the void can be observed in the interior of theupper wiring groove. This pattern dependency of void may be attributedto the phenomenon that the void tends to generate at a location whichminimizes the surface free energy of the void.

The void may become a cause for a disconnection of wiring and for adeterioration of electromigration resistance or stress migrationresistance, and hence some measures are required to be taken to solvethe problems in actual use.

Followings are specific embodiments of the aforementioned method [1] ofmanufacturing a semiconductor device.

(a) The wiring groove is formed after the contact hole is formed.

(b) A barrier film or a CMP stopper layer is formed after the contacthole is formed, and then the wiring groove is formed.

(c) The contact hole is formed after the wiring groove is formed.

(d) A barrier film or a CMP stopper layer is formed after the wiringgroove is formed, and then the contact hole is formed.

(e) A barrier film or a CMP stopper layer is formed after the contacthole and the wiring groove are formed.

(f) The contact hole and the wiring groove are formed after a barrierfilm or a CMP stopper layer is formed on the insulating film.

[2] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming a first insulating film on a semiconductor substrate providedwith a conductive layer;

forming a contact hole through the first insulating film to a depthreaching to the conductive layer;

forming a substitutive film in an interior of contact hole;

forming a second insulating film all over an upper surface of thesubstrate;

forming a wiring groove in the second insulating film in a manner toconnect it with the substitutive film;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are specific embodiments of the aforementioned method [2] ofmanufacturing a semiconductor device.

(a) The contact hole is formed by means of RIE after an RIE stopperlayer is formed on the first insulating film.

(b) A barrier film is formed after the contact hole is formed.

[3] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer;

forming a substitutive film at least in an interior of the contact hole;

forming a wiring groove in the insulating film;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are a specific embodiment of the aforementioned method [3] ofmanufacturing a semiconductor device.

(a) The contact hole is formed after a CMP stopper layer is formed onthe first insulating film.

Followings are specific embodiments of the aforementioned methods [1] to[3] of manufacturing a semiconductor device.

(a) A substitutive film is formed all over the upper surface of thesubstrate to such a thickness that the substitutive film overflows fromthe contact hole, and then the substitutive film is etched back so as toselectively leave the substitutive film in the interior of the contacthole.

(b) A substitutive film is formed by means of a CVD method all over theupper surface of the substrate to such a thickness that the substitutivefilm overflows from the contact hole, and then the substitutive film isetched back so as to selectively leave the substitutive film in theinterior of the contact hole.

(c) A substitutive film is formed by means of a CVD method all over theupper surface of the substrate to such a thickness that the substitutivefilm overflows from the contact hole, and then the substitutive film isetched back by means of a CDE etch-back method, an RIE etch-back method,a CMP method or at least two methods selected from these methods so asto selectively leave the substitutive film in the interior of thecontact hole.

(d) The substitutive film is formed by means of a selective CVD methodor a plating method.

(e) In subsequent to the formation of the absorption layer, thesubstrate is subjected to a heat treatment thereby to allow thesubstitutive film to be substituted by the conductive film and to allowthe substitutive film to be absorbed by the absorption layer.

(f) In simultaneous with the formation of the absorption layer, thesubstrate is subjected to a heat treatment thereby to allow thesubstitutive film to be substituted by the conductive film and to allowthe substitutive film to be absorbed by the absorption layer.

(g) The conductive film is formed by means of a sputtering method or aCVD method.

(h) The conductive film is formed by means of a reflow so as to cover astep portion formed by a formation of the wiring groove.

(i) The absorption layer is formed by means of a sputtering method or aCVD method.

(j) The absorption layer is formed without breaking vacuum after theconductive film is formed in a vacuum, or the absorption layer is formedafter a native oxide film and/or impurities are removed subsequent tothe formation of the conductive film in a vacuum.

(k) The removal of the absorption layer and the product, and the workingof the conductive film are all performed by means of a CMP method, anRIE etch-back method, a CDE etch-back method, a wet etching method or acombination of at least two methods selected from these methods.

(l) The conductive film is formed of a material which exhibits a lowervolume density when it is employed in a form of a non-crystallinestructure as compared with when it is employed in a form of acrystalline structure.

(m) The conductive film is formed of a porous crystalline material or anamorphous material.

(n) The conductive film contains at least partially a crystal defect ora region containing a rare gas.

[4] This invention further provides; a semiconductor device whichcomprises:

a semiconductor substrate provided with a conductive layer;

an insulating film formed on the substrate and having a flat uppersurface;

a plug and a wiring formed on the insulating film and filled ininteriors of a contact hole connected with the conductive layer and of awiring groove, respectively; and

a barrier film interposed between a side wall of the contact hole andthe conductive layer, between a side wall of the wiring groove and thewiring, and between a bottom of the wiring groove and the wiring.

[5] This invention further provides; a semiconductor device whichcomprises:

a semiconductor substrate provided with a conductive layer;

an insulating film formed on the substrate and having a flat uppersurface;

a plug and a wiring formed on the insulating film and filled ininteriors of a contact hole connected with the conductive layer and of awiring groove, respectively; and

a barrier film interposed between a side wall and bottom of the contacthole and the conductive layer, and between a side wall and bottom of thewiring groove and the wiring.

[6] This invention further provides; a semiconductor device whichcomprises:

a semiconductor substrate provided with a conductive layer;

an insulating film formed on the substrate and having a flat uppersurface;

a plug and a wiring formed on the insulating film and filled ininteriors of a contact hole connected with the conductive layer and of awiring groove, respectively; and

a barrier film interposed between a side wall and bottom of the contacthole and the conductive layer.

[7] This invention further provides; a semiconductor device whichcomprises:

a semiconductor substrate provided with a conductive layer;

an insulating film formed on the substrate and having a flat uppersurface;

a plug and a wiring formed on the insulating film and filled ininteriors of a contact hole connected with the conductive layer and of awiring groove, respectively; and

a barrier film interposed between a side wall and bottom of the wiringgroove and the conductive layer.

Followings are specific embodiments of the aforementioned semiconductordevices [4] to [7].

(a) A CMP stopper layer or an insulating barrier film is formed on anentire surface of insulating film excluding a region where the contacthole and the wiring groove are located.

(b) A barrier film is formed on a surface of the wiring.

(c) The conductive layer, the wiring and the plug are all formed of thesame material.

(d) The conductive layer, the wiring and the plug are all formed of Al,an Al alloy, Cu or a Cu alloy.

(e) The conductive layer, the wiring and the plug are all formed of Al,an Al alloy, Cu or a Cu alloy, and the barrier film is formed of arefractory metal or a refractory metal compound.

[8] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film by means of a CVD method to a thicknesswhich enables it to cover inner surfaces of the contact hole and thewiring groove and to incompletely fill interiors of the contact hole andthe wiring groove;

filling almost entirely the interiors of the contact hole and the.wiring groove with a conductive film;

forming an absorption layer on the conductive film;

filling the interiors of the contact hole and the wiring groovecompletely with the conductive film by substituting the conductive filmfor the substitutive film and by allowing the substitutive film to be.absorbed by the absorption layer under a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

[9] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film by means of a CVD method to a thicknesswhich enables it to cover inner surfaces of the contact hole and thewiring groove and to incompletely fill interiors of the contact hole andthe wiring groove;

filling almost entirely the interiors of the contact hole and the wiringgroove with a conductive film;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove completely with theconductive film by substituting the conductive film for the substitutivefilm and by allowing the substitutive film to be absorbed by theabsorption layer under a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are specific embodiments of the aforementioned methods [8]and [9] of manufacturing a semiconductor device.

(a) The conductive film is formed by means of a reflow method, anon-selective CVD method, a selective CVD method or a plating method,thereby filling almost entirely the interiors of the contact hole andthe wiring groove with the conductive film.

(b) In subsequent to the formation of the conductive film by means of asputtering method, the interiors of the contact hole and the wiringgroove are filled almost entirely with the conductive film by means of areflow method which enables the conductive film to be fluidized withheating.

(c) In subsequent to the formation of the conductive film by means of asputtering method without heating, the conductive film is additionallyformed by means of a sputtering method with heating, and then theinteriors of the contact hole and the wiring groove are filled with theconductive film by means of a two-step reflow method which enables theconductive film to be fluidized.

(d) In subsequent to the formation of the conductive film by means of adirectional sputtering method without heating, the conductive film isadditionally formed by means of a sputtering method with heating, andthen the interiors of the contact hole and the wiring groove are filledwith the conductive film by means of a two-step reflow method whichenables the conductive film to be fluidized.

(e) A barrier film is formed after the contact hole and the wiringgroove are formed.

[10] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film in the interiors of the contact hole and thewiring groove;

removing a native oxide film and/or impurities on a surface of thesubstitutive film;

forming a conductive film on a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are specific embodiments of the aforementioned method [10] ofmanufacturing a semiconductor device.

(a) The native oxide film and/or impurities are removed by means of awet etching, a physical etching or a chemical etching.

(b) The native oxide film and/or impurities are removed by means of awet etching, and then the surface of the substitutive film is subjectedto a hydrogen termination treatment.

(c) After the native oxide film and/or impurities are removed by meansof a physical etching, the substrate is kept in a vacuum until theconductive film is formed.

(d) After the native oxide film and/or impurities are removed by meansof a chemical etching, the substrate is kept in a vacuum until theconductive film is formed.

[11] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film to such a thickness that the interiors ofthe contact hole and the wiring groove are filled with the substitutivefilm and the substitutive film overflows from the contact hole and fromthe wiring groove;

removing the substitutive film in a vacuum by means of an RIE etch-backmethod or a CDE etch-back method to such an extent that the substitutivefilm is left remained at least in the interiors of the contact hole andthe wiring groove;

forming a conductive film on a region comprising the contact hole andthe wiring groove without breaking vacuum;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

[12] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film to such a degree that the interiors of the.contact hole and the wiring groove are filled with the substitutivefilm;

forming a conductive film on a region comprising the contact hole andthe wiring groove in a heated condition which enables a native oxidefilm formed on a surface of the substitutive film to be decomposedthrough a reaction between the conductive film and the substitutive filmduring the formation of the conductive film;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are a specific embodiment of the aforementioned method [12]of manufacturing a semiconductor device.

(a) The conductive film is formed by means of a thermal sputtering.

[13] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming a conductive layer on a semiconductor substrate;

forming an insulating film to cover the conductive layer formed on thesubstrate;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

removing a native oxide film and/or impurities on a surface of thesubstitutive film, which has been exposed at a bottom of the contacthole;

forming a substitutive film at least in the interiors of the contacthole;

forming a conductive film on a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are specific embodiments of the aforementioned method [13] ofmanufacturing a semiconductor device.

(a) After the native oxide film and/or impurities are removed in avacuum by means of a physical etching or a chemical etching employing ahalogen gas as an etching gas, the substrate is kept in a vacuum untilthe substitutive film is formed.

(b) After the native oxide film and/or impurities are removed by meansof a physical etching or a chemical etching employing a halogen gas asan etching gas, the conductive film is formed by making use of asingle-wafer processing type CVD apparatus, wherein the entire processbeginning from the removal of the native oxide film and/or impuritiesuntil the formation of the substitutive film is finished is performed ina vacuum so as to prevent a reoxidation of the surface of the conductivelayer.

(c) After the native oxide film and/or impurities are removed by meansof a physical etching or a chemical etching employing a halogen gas asan etching gas, the conductive film is formed by making use of ahigh-speed single-wafer processing type CVD apparatus, wherein theentire process beginning from the removal of the native oxide filmand/or impurities until the formation of the substitutive film isfinished is performed in a vacuum so as to prevent a reoxidation of thesurface of the conductive layer.

(d) After the native oxide film and/or impurities are removed by meansof a chemical etching employing a halogen gas as an etching gas, theconductive film is formed by making use of a batch type CVD apparatus,wherein the entire process beginning from the removal of the nativeoxide film and/or impurities until the formation of the substitutivefilm is finished is performed in a vacuum so as to prevent a reoxidationof the surface of the conductive layer.

(e) The native oxide film and/or impurities are removed in a vacuum bymeans of a reduction reaction employing a reducing agent.

(f) After the native oxide film and/or impurities are removed, a barrierfilm is formed.

[14] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

substituting a conductive film for a substitutive film in the interiorof a contact hole and/or a wiring groove, the conductive film beingformed in advance on the substitutive film, rendering the substitutivefilm to be absorbed by an absorption layer to form a compound, wherebyfilling the contact hole and/or the wiring groove with the conductivefilm; and

wherein the conductive film is formed to have a roughened surfacewhereby increasing a contact area thereof with the absorption layer.

Followings are a specific embodiment of the aforementioned method [14]of manufacturing a semiconductor device.

(a) The conductive film is formed in a heated condition thereby forminga roughened surface.

[15] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

substituting a conductive film for a substitutive film in the interiorof a contact hole and/or a wiring groove, the conductive film beingformed in advance on the substitutive film, and rendering thesubstitutive film to be absorbed by an absorption layer to form acompound, whereby filling the contact hole and/or the wiring groove withthe conductive film; and

wherein the conductive film formed is heat-treated whereby rendering theelement of the substitutive film to diffuse into the conductive film,and then the absorption layer formed subsequently is heat-treatedwhereby rendering the element diffused into the conductive film to beabsorbed by the absorption layer.

[16] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

substituting a conductive film for a substitutive film in the interiorof a contact hole and/or a wiring groove, the conductive film beingformed in advance on the substitutive film, and rendering thesubstitutive film to be absorbed by an absorption layer to form acompound, whereby filling the contact hole and/or the wiring groove withthe conductive film; and

wherein the conductive film and the absorption layer are successivelyformed and then heat-treated whereby rendering the element of thesubstitutive film in the conductive film to be absorbed by theabsorption layer.

Followings are a specific embodiment of the aforementioned method [16]of manufacturing a semiconductor device.

(a) After the heat treatment, the heat treatment for rendering theelement of the substitutive film in the conductive film to be absorbedby the absorption layer is performed at least once more.

[17] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film at least in the interiors of the contacthole and the wiring groove;

forming a conductive film containing a plurality of absorption bodies ona region comprising the contact hole and the wiring groove;

filling the interiors of the contact hole and the wiring groove with theconductive film by substituting the conductive film for the substitutivefilm and by allowing the substitutive film to be absorbed by theabsorption layer under a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

[18] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer;

forming a substitutive film in the interior of the contact hole;

forming a conductive film having at the bottom thereof a plurality ofabsorption bodies, the absorption bodies also formed on a regionexcluding the contact hole;

filling the interior of the contact hole with the conductive film bysubstituting the conductive film for the substitutive film and byallowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole by working theconductive film so as to selectively leave the conductive film in theinterior of the contact hole.

[19] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth at leastreaching to the conductive layer and forming a substitutive film in aninterior of a wiring groove;

forming a conductive film having at the bottom thereof a plurality ofabsorption bodies, the absorption bodies also formed on a regionexcluding the contact hole;

filling the interiors of the contact hole and the wiring groove with theconductive film by substituting the conductive film for the substitutivefilm and by allowing the substitutive film to be absorbed by theabsorption layer under a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

[20] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming an absorption layer on the insulating film;

forming a contact hole through the insulating film to a depth at leastreaching to the conductive layer and a wiring groove, and working theabsorption layer to obtain a plurality of partitioned absorption bodies;

forming a substitutive film in the interiors of the contact hole and thewiring groove;

forming a conductive film in a region comprising the contact hole, thewiring groove and the plurality of absorption bodies;

filling the interiors of the contact hole and the wiring groove with theconductive film by substituting the conductive film for the substitutivefilm and by allowing the substitutive film to be absorbed by theabsorption layer under a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

[21] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film at least in the interiors of the contacthole and the wiring groove;

forming a conductive film not containing an absorption layer on a regioncomprising the contact hole and the wiring groove;

filling the interiors of the contact hole and the wiring groove with theconductive film by substituting the conductive film for the substitutivefilm and by allowing the substitutive film to be absorbed by theabsorption layer under a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are specific embodiments of the aforementioned methods [20]and [21] of manufacturing a semiconductor device.

(a) The conductive film is formed in such a manner that a plurality ofabsorption bodies are existed in the same layer.

(b) The conductive film is formed by making use of a shadow mask in sucha manner that a plurality of absorption bodies are existed at a desiredlocation in the same layer.

(c) The conductive film is formed in such a manner that a plurality ofabsorption bodies are existed at a desired location in the same layerand at desired plural levels within the same layer.

(d) The conductive film is formed in such a manner that a plurality ofabsorption bodies are existed at a desired location in the same layerand at desired plural levels within the same layer, each absorptionlayer being horizontally off-set from another absorption layer disposedover or below the each absorption layer.

(e) The conductive film is formed by making use of a shadow mask in sucha manner that a plurality of absorption bodies are existed at a desiredlocation in the same layer and at desired plural levels within the samelayer, each absorption layer being horizontally off-set from anotherabsorption layer disposed over or below the each absorption layer.

(f) The plurality of absorption bodies contained in the conductive filmare respectively formed as a laminate film constituting together withthe conductive film a laminate layer.

(g) The quantity of the plurality of absorption bodies disposed over alayer containing a relatively large quantity of the substitutive film ismade larger as compared with that of absorption bodies disposed over alayer containing a relatively small quantity of the substitutive film.

(h) The plurality of absorption bodies are formed by making use ofion-implanting.

(i) The absorption bodies are constituted by fine particles.

(j) The conductive film containing a plurality of absorption bodiestherein is formed by depositing fine particles consisting of aconstituent material of the conductive film and a constituent materialof the absorption bodies on a region of substrate comprising the contacthole and the wiring groove.

(k) The conductive film containing a plurality of absorption bodiestherein is formed by coating a dispersion containing fine particlesconsisting of a constituent material of the conductive film and aconstituent material of the absorption bodies on a region of substratecomprising the contact hole and the wiring groove.

(l) The conductive film containing a plurality of absorption bodiestherein is formed of a film comprising a mixture consisting of aconstituent material of the conductive film and a constituent materialof the absorption bodies.

(m) The conductive film containing a plurality of absorption bodiestherein is formed of an amorphous film comprising a mixture consistingof a constituent material of the conductive film and a constituentmaterial of the absorption bodies.

(o) The conductive film containing a plurality of absorption bodiestherein is formed by means of sputtering method employing a first targetconsisting mainly of a constituent material of the conductive film and asecond target consisting mainly of a constituent material of theabsorption bodies.

(p) The conductive film containing a plurality of absorption bodiestherein is formed by means of sputtering method employing a sputteringtarget comprising a mixture of a constituent material of the conductivefilm and a constituent material of the absorption bodies.

[22] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

substituting a conductive film for a substitutive film in the interiorof a contact hole and/or a wiring groove, the conductive film beingformed in advance on the substitutive film, and rendering thesubstitutive film to be absorbed by an absorption layer to form acompound, whereby filling the contact hole and/or the wiring groove withthe conductive film; and

wherein the step is performed by repeating a heat treatment at leasttwice, each heat treatment being performed at a different temperaturefrom each other, whereby rendering the element of the substitutive filmto be substituted by the conductive film, and rendering the substitutivefilm to be absorbed by the absorption layer.

Followings are specific embodiments of the aforementioned method [22] ofmanufacturing a semiconductor device.

(a) The heat treatment is performed in such a manner that a temperatureof the final heat treatment is the lowest among that of other heattreatment(s).

(b) The heat treatment is performed at a temperature which permits aformation of the compound as well at a temperature which does permit aformation of the compound.

[23] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

substituting a conductive film for a substitutive film in the interiorof a contact hole and/or a wiring groove, the conductive film beingformed in advance on the substitutive film, and rendering thesubstitutive film to be absorbed by an absorption layer to form acompound, whereby filling the contact hole and/or the wiring groove withthe conductive film; and

wherein the step is performed at first by means of heat treatment,whereby rendering the element of the substitutive film to be substitutedby the conductive film, and rendering the substitutive film to beabsorbed by the absorption layer, whereby producing the compound, andthen by annealing the conductive film.

[24] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of substituting a conductivefilm for a substitutive film in the interior of a contact hole and/or awiring groove, the conductive film being formed in advance on thesubstitutive film, and rendering the substitutive film to be absorbed byan absorption layer to form a compound, whereby filling the contact holeand/or the wiring groove with the conductive film; and which is featuredto include the steps of:

filling the interior of a contact hole and/or a wiring groove with aconductive film by substituting the conductive film formed on thesubstitutive film for the substitutive film filled in the interior of acontact hole and/or a wiring groove, and by rendering the substitutivefilm to be absorbed by a first absorption layer to form a firstcompound;

removing the first compound and the conductive film disposed on a regionother than the contact hole and the wiring groove;

forming a second absorption layer on a surface of the conductive filmleft remained after the previous step;

forming a second compound by rendering the substitutive film leftremained in the conductive film to be absorbed by the second absorptionlayer by making use of a heat treatment; and

removing the second absorption layer and the second compound.

[25] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

filling a contact hole and/or a wiring groove with a conductive filmthrough a substitution/absorption treatment, the substitution/absorptiontreatment being performed by substituting the conductive film for asubstitutive film in the contact hole and/or the wiring groove, theconductive film being formed in advance on the substitutive film, and atthe same time, by rendering the substitutive film to be absorbed by anabsorption layer to form a compound; and

wherein the step is performed by introducing into the conductive film anelement which differs from constituent materials of the conductive filmand the absorption layer during or after the substitution/absorptiontreatment.

Followings are specific embodiments of the aforementioned method [25] ofmanufacturing a semiconductor device.

(a) The conductive film is formed of a single conductive element.

(b) The element is an element which is capable of lowering the solidsolution limit of the constituent material of the substitutive film inthe conductive film after the substitution/absorption treatment, or anelement which is capable of improving electromigration resistance orstress migration resistance of the conductive film.

(c) The element is an element which is capable of improvingelectromigration resistance and/or stress migration resistance of theconductive film after the substitution/absorption treatment.

(d) The element is introduced into the conductive film by forming a filmcontaining the element on a surface of at least one of the substitutivefilm, the conductive film and the absorption layer.

(e) The element is introduced into the conductive film by employing atleast one of the substitutive film, the conductive film and theabsorption layer, each containing the element.

(f) The element is introduced into the conductive film by forming a filmcontaining the element and then rendering the element to enter into theconductive film by making use of a heat treatment.

(g) The element is introduced into the conductive film by forming a filmcontaining the element and then rendering the element to enter into theconductive film by making use of a heat treatment, and a barrier film isformed at an interface between the film containing the element and theinsulating film so as to prevent the film containing the element fromdirectly contacting with the insulating film in which the contact holeand/or the wiring groove is formed.

(h) The element is introduced into the conductive film by forming a filmcontaining the element and then rendering the element to enter into theconductive film by making use of a heat treatment, and a barrier film isformed at an interface between the film containing the element and theinsulating film so as to prevent the film containing the element fromdirectly contacting with the insulating film in which the contact holeand/or the wiring groove is formed, the barrier film being selected fromthe group consisting of a mono-layer film (such as an SiN film, a TiNfilm, a TaN film or WN film); and a laminate film (such as a Ti—Si—Nfilm, a W—Si—N film or Ta—Si—N film).

[26] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

filling a contact hole and/or a wiring groove with a conductive filmthrough a substitution/absorption treatment, the substitution/absorptiontreatment being performed by substituting the conductive film for asubstitutive film in the contact hole and/or the wiring groove, theconductive film being formed in advance on the substitutive film, and byrendering the substitutive film to be absorbed by an absorption layer toform a compound; and

wherein a constituent material of the substitutive film to be combinedwith a constituent material of the absorption layer is selected so as toform the compound, and a diffusion velocity of the constituent materialof the substitutive film in the conductive film at thesubstitution/absorption treatment temperature is higher than a diffusionvelocity of the constituent material of the absorption layer in theconductive film.

Followings are specific embodiments of the. aforementioned method [26]of manufacturing a semiconductor device.

(a) A compound comprising the constituent material of substitutive filmand the constituent material of absorption layer is produced at a fasterrate than a compound comprising the constituent material of conductivefilm and the constituent material of absorption layer.

(b) A combination between the constituent material of substitutive filmand the constituent material of conductive film is selected so as toproduce a eutectic in the substitution/absorption treatment.

[27] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed in the same insulating film with aconductive film through a substitution between the substitutive film andthe conductive film formed on the substitutive film, and which isfeatured to include the steps of:

forming the conductive film in the interior of the wiring groove afterthe substitutive film is formed in the interior of the contact hole; and

filling a contact hole and/or a wiring groove with a conductive film bysubstituting the conductive film for the substitutive film and byrendering the substitutive film to precipitate on the surface of theconductive film through a heat treatment.

[28] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed in the same insulating film with aconductive film through a substitution between the substitutive film andthe conductive film formed on the substitutive film, and which isfeatured to include the steps of:

forming the substitutive film in the interiors of the contact hole andthe wiring groove;

forming the conductive film in a region comprising the contact hole andthe wiring groove;

substituting the conductive film for the substitutive film and renderingthe substitutive film to precipitate on the surface of the conductivefilm through a heat treatment; and

removing the substitutive film protruded from the wiring groove, wherebyforming a plug comprising the conductive film in the contact hole and/ora wiring comprising the conductive film in the wiring groove.

[29] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed in the same insulating film with aconductive film through a substitution between the substitutive film andthe conductive film formed on the substitutive film, and which isfeatured to include the steps of:

forming the substitutive film in the interiors of the contact hole andthe wiring groove;

forming the conductive film in a region comprising the contact hole andthe wiring groove;

forming a precipitation-promoting layer for precipitating the element ofthe substitutive film in a region neighboring to the conductive film;

substituting the conductive film for the substitutive film and renderingthe substitutive film to precipitate on the surface of theprecipitation-promoting layer through a heat treatment; and

removing the substitutive film protruded from the wiring groove, wherebyforming a plug comprising the conductive film in the contact hole and/ora wiring comprising the conductive film in the wiring groove.

Followings are a specific embodiment of the aforementioned method [29]of manufacturing a semiconductor device.

(a) The precipitation-promoting layer is formed of the same element asthat of the substitutive film.

[30] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed in the same insulating film with aconductive film through a substitution between the substitutive film andthe conductive film formed on the substitutive film, and which isfeatured to include the steps of:

forming the substitutive film in the interiors of the contact hole andthe wiring groove;

forming the conductive film in a region comprising the contact hole andthe wiring groove;

forming a precipitation-promoting layer for precipitating the element ofthe substitutive film in the conductive film, theprecipitation-promoting layer containing a rare gas, crystal defects orimpurities;

substituting the conductive film for the substitutive film and renderingthe substitutive film to precipitate on the surface of theprecipitation-promoting layer through a heat treatment; and

removing the substitutive film protruded from the wiring groove, wherebyforming a plug comprising the conductive film in the contact hole and/ora wiring comprising the conductive film in the wiring groove.

[31] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed with a conductive film through asubstitution between the substitutive film formed in the contact holeand/or the wiring groove and the conductive film formed on thesubstitutive film, and which is featured to include the steps of:

substituting the conductive film for the substitutive film by making useof a heat treatment in a gaseous atmosphere containing a materialcapable of producing a compound with the substitutive film, andrendering the compound to precipitate at an interface between theconductive film and the wiring groove and/or at an interface between thecontact hole and the wiring groove; and

removing the conductive film, the substitutive film and the compoundwhich are protruded from the wiring groove.

Followings are a specific embodiment of the aforementioned method [31]of manufacturing a semiconductor device.

(a) The gaseous atmosphere contains N, O, H or at least two kinds ofelement selected from N, O and H.

[32] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed with a conductive film through asubstitution between the substitutive film formed in the contact holeand/or the wiring groove and the conductive film formed on thesubstitutive film, and which is-featured to include a step of:

substituting the conductive film for the substitutive film by making useof a heat treatment in a gaseous atmosphere containing a materialcapable of producing a compound with the substitutive film, and removingthe substitutive film by making use of a gas of the compound to beformed between the substitutive film and the material.

Followings are a specific embodiment of the aforementioned method [32]of manufacturing a semiconductor device.

(a) The gaseous atmosphere contains F, Br, Cl, I or at least two kindsof element selected from F, Br, Cl and I.

(b) A combination of a constituent material of the substitutive film, aconstituent material of conductive film and a constituent material ofthe gaseous atmosphere is selected such that a compound to be producedthrough a reaction between constituent materials of the substitutionfilm and gaseous atmosphere can be produced at a lower temperature asthat of a compound to be produced through a reaction between constituentmaterials of the substitution film and conductive film.

(c) The gaseous atmosphere contains an ionized gas.

(d) A combination between the constituent material of substitutive filmand the constituent material of conductive film is selected so as toproduce a eutectic in the heat treatment.

(e) The constituent material of conductive film is Cu or a Cu alloy, andthe constituent material of substitutive film is W, Ta, Nb, Bi, Si, Snor Ti.

[33] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of forming a laminatedinsulating structure comprising at least two insulating films, eachinsulating film being provided with a contact hole and a wiring groove,each deposited with a substitutive film in the interior thereof, thestep comprises the sub-steps of:

filling an interior of wiring groove of the uppermost insulating filmwith among the wiring grooves formed in the insulating films;

forming a conductive film on the uppermost insulating film;

forming an absorption layer in the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of rendering the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

Followings are specific embodiments of the aforementioned method [33] ofmanufacturing a semiconductor device.

(a) Each substitutive film filled in the wiring groove is connected witheach other via the substitutive film filled in the contact hole.

(b) All of the substitutive films disposed within the insulating filmsof the laminated insulating structure are concurrently substituted bythe conductive film by means of the heat treatment.

(c) Each substitutive film disposed within the insulating films of thelaminated insulating structure is at least partially contacted with theabsorption layer via the conductive film before the heat treatment.

(d) The substitutive film filled in the wiring groove formed in theuppermost insulating film of the laminated insulating structure iscontacted with the absorption layer via the conductive film.

(e) The substitutive film is formed via a refractory metal film or via ahigh-melting point alloy film in the contact hole and the wiring grooveformed in at least one of the insulating films of the laminatedinsulating structure before the heat treatment.

(f) A portion of the contact hole is not required to be employed in anelectric circuit.

(g) The manufacturing method further comprises a step of forming aninsulating film provided with a plurality of wiring grooves each filledwith the substitutive film, which comprises the sub-steps of; forming aplurality of wiring grooves on the surface of the insulating film;forming the substitutive film all over the surface of the insulatingfilm; and removing all of the substitutive film excluding those formedin a region of the plurality of wiring grooves.

[34] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming a contact hole in an insulating film;

filling the contact hole with a plug containing a refractory metal;

forming a wiring groove in the insulating film;

forming a conductive film in a region including the wiring groove to athickness, thereby allowing the conductive film to be protrude from thewiring groove;

removing the conductive film to an extent to allow the surface of theinsulating film to be exposed, thereby filling the wiring groove with awiring consisting of the conductive film; and

forming a high-melting point conductive film containing a refractorymetal on the wiring.

Followings are specific embodiments of the aforementioned method [34] ofmanufacturing a semiconductor device.

(a) The wiring groove is formed in a region including the plug in amanner to allow the plug to be left in the interior of the wiringgroove.

(b) The plug is formed by means of a selective. CVD method in a processof filling the contact hole with the plug.

(c) A conductive film containing a refractory metal is formed to aheight protruding from the contact hole in a region including thecontact hole by means of a CVD method, and then a surface of theconductive film is etched back by means of a CMP method, a CDE etch-backmethod or an RIE etch-back method so as to fill the contact hole with aplug containing the refractory metal.

(d) A conductive film containing a refractory metal is formed as a plugin a region including the contact hole, and then the conductive film isfluidized by means of a reflow method so as to fill the wiring groovewith the conductive film.

(e) The wiring groove is filled with a substitutive film, a conductivefilm is deposited on the substitutive film, and then the substitutivefilm is substituted by the conductive film, whereby forming theconductive film in a region including the wiring groove to a heightprotruding from the wiring groove.

(f) The plug is directly contacted with the high melting pointconductive film.

(g) A treatment for removing a native oxide film by means of a physicaletching or a wet etching is performed prior to the formation of thehigh-melting point conductive film.

(h) The plug is a tungsten plug.

[35] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

filling a contact hole and/or a wiring groove with a conductive film bysubstituting the conductive film for a substitutive film in the contacthole and/or the wiring groove, the conductive film being formed inadvance on the substitutive film, and by rendering the substitutive filmto be absorbed by an absorption layer; and

wherein the absorption layer, a compound formed in the above process ofabsorbing the substitutive film by the absorption layer, and theconductive film are successively removed.

Followings are specific embodiments of the aforementioned method [35] ofmanufacturing a semiconductor device.

(a) The absorption layer, the compound and the conductive film areremoved by means of a CMP method.

(b) The absorption layer is removed by means of a wet etching, a CDEetch-back method or an RIE etch-back method, and the compound and theconductive film are removed by means of a CMP method.

(c) The absorption layer and the compound are removed by means of a wetetching, a CDE etch-back method or an RIE etch-back method, and theconductive film is removed by means of a CMP method.

(d) The absorption layer, the compound and the conductive film areremoved by means a wet etching, a CDE etch-back method or an RIEetch-back method.

[36] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film containing a diffusion-promoting agent inthe contact hole and/or the wiring groove;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove;

the diffusion-promoting agent functioning to promote an mutual diffusionbetween the substitutive film and the conductive film.

Followings are a specific embodiment of the aforementioned method [36]of manufacturing a semiconductor device.

(a) The diffusion-promoting agent is formed of boron, the conductivefilm is formed of an amorphous silicon film, the absorption layer isformed of titanium, and the compound is titanium silicide.

[37] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film containing a diffusion-inhibiting agent inthe contact hole and/or the wiring groove;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove;

the diffusion-inhibiting agent functioning to react with the absorptionfilm to form a diffusion-inhibiting film to inhibit the absorption filmfrom diffusing into the conductive film, and the location of thediffusion-inhibiting film being at or near an interface between theabsorption film and the conductive film.

Followings are specific embodiments of the aforementioned method [37] ofmanufacturing a semiconductor device.

(a) The diffusion-inhibiting agent is formed of boron, the conductivefilm is formed of an amorphous silicon film, the absorption layer isformed of titanium, the compound is titanium silicide, and thediffusion-inhibiting film is a titanium boride film.

(b) The substitutive film is formed by means of a CVD method employing amixed gas containing plural kinds of feed gas.

(c) As the substitutive film, a boron-containing amorphous silicon filmis formed by means of a CVD method employing a mixed gas containingdisilane gas and diborane gas.

(d) As the substitutive film, a boron-containing amorphous silicon filmis formed by means of a CVD method employing a mixed gas containingdisilane gas and diborane gas at a temperature range which does notcause any deformation of the plug due to a thermal stress.

(e) As the substitutive film, a boron-containing amorphous silicon filmis formed by means of a CVD method employing a mixed gas containingdisilane gas and diborane gas at a temperature of not more than 400° C.which does not cause any deformation of the plug due to a thermalstress.

[38] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film in the contact hole and the wiring groove;

successively forming an absorption layer and a conductive film at aregion comprising the contact hole and the wiring groove;

filling the interiors of the contact hole and the wiring groove with theconductive film by substituting the conductive film for the substitutivefilm and by allowing the substitutive film to be absorbed by theabsorption layer under a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove.

[39] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer;

forming a substitutive film in the contact hole;

successively forming an absorption layer and a conductive film at aregion comprising the contact hole;

filling the interior of the contact hole with the conductive film bysubstituting the conductive film for the substitutive film and byallowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole by working theconductive film so as to selectively leave the conductive film in theinterior of the contact hole.

[40] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film in the contact hole and/or the wiringgroove;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming a diffusion-inhibiting layer on the conductive film;

forming an absorption layer on the diffusion-inhibiting layer andfilling the interiors of the contact hole and the wiring groove with theconductive film by substituting the conductive film for the substitutivefilm and by allowing the substitutive film to be absorbed by theabsorption layer under a heat treatment; and

forming a plug comprising the conductive film in the contact hole aswell as a wiring comprising the conductive film in the wiring groove byworking the conductive film so as to selectively leave the conductivefilm in the interiors of the contact hole and the wiring groove.

[41] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film in the contact hole and/or the wiringgroove;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film and forming adiffusion-inhibiting layer and filling the interiors of the contact holeand the wiring groove with the conductive film by substituting theconductive film for the substitutive film and by allowing thesubstitutive film to be absorbed by the absorption layer under a heattreatment; and

forming a plug comprising the conductive film in the contact hole aswell as a wiring comprising the conductive film in the wiring groove byworking the conductive film so as to selectively leave the conductivefilm in the interiors of the contact hole and the wiring groove;

the heat treatment being performed at first at a lower temperaturethereby to form the diffusion-inhibiting layer, and then at a highertemperature thereby to accelerate the absorption of the substitutivefilm by the absorption layer.

[42] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate provided with aconductive layer;

forming a contact hole through the insulating film to a depth reachingto the conductive layer and forming a wiring groove in the insulatingfilm;

forming a substitutive film containing a diffusion-promoting agent inthe contact hole and/or the wiring groove;

forming a conductive film at a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film, and filling theinteriors of the contact hole and the wiring groove with the conductivefilm by substituting the conductive film for the substitutive film andby allowing the substitutive film to be absorbed by the absorption layerunder a heat treatment; and

removing a compound formed in the process of allowing the substitutivefilm to be absorbed by the absorption layer, and forming a plugcomprising the conductive film in the contact hole as well as a wiringcomprising the conductive film in the wiring groove by working theconductive film so as to selectively leave the conductive film in theinteriors of the contact hole and the wiring groove;

a combination of the temperature and time of the heat treatment beingcontrolled such that the total of: the resistive component of theconductive film originating from the constituent material of thesubstitutive film remaining in the conductive film filled in the contacthole and wiring groove and the resistive component of the conductivefilm originating from the constituent material of the absorption layerremaining in the conductive film filled in the contact hole and wiringgroove becomes minimum or nearly minimum.

[43] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

filling a contact hole and/or a wiring groove with a conductive filmthrough a substitution/absorption treatment, the substitution/absorptiontreatment being performed by substituting the conductive film for asubstitutive film in the contact hole and/or the wiring groove, theconductive film being formed in advance on the substitutive film, and byrendering the substitutive film to be absorbed by an absorption layer toform a compound; and

wherein the substitution/absorption treatment is performed in a gaseousatmosphere which enables the constituent material of the absorptionlayer that has a been diffused through the conductive film to bedischarged out of the conductive film; or an additional heat treatmentis performed after the substitution/absorption treatment in a gaseousatmosphere which enables the constituent material of the absorptionlayer that is remained in the conductive film to be discharged out ofthe conductive film.

[44] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

filling a contact hole and/or a wiring groove with a conductive film bysubstituting the conductive film formed on a substitutive film for thesubstitutive film filled in the contact hole and/or the wiring grooveand by rendering the substitutive film to be absorbed by an absorptionlayer; and

wherein a compound formed in the absorption of the substitutive film bythe absorption layer is removed, and the conductive film is worked toselectively leave the conductive film in the interiors of the contacthole and the wiring groove, whereby forming a plug comprising theconductive film in the contact hole as well as a wiring comprising theconductive film in the wiring groove; and then a heat treatment isperformed in a gaseous atmosphere which enables the constituent materialof the absorption layer that is remained in the conductive film to bedischarged out of the conductive film.

Followings are a specific embodiment of the aforementioned methods [42]to [44] of manufacturing a semiconductor device.

(a) The gaseous atmosphere contains N, O, H, C, B or at least two kindsof element selected from N, O, H, C and B.

[45] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

filling a contact hole and/or a wiring groove with a conductive filmthrough a substitution/absorption treatment, the substitution/absorptiontreatment being performed by substituting the conductive film for asubstitutive film in the contact hole and/or the wiring groove, theconductive film being formed in advance on the substitutive film, and byrendering the substitutive film to be absorbed by an absorption layer toform a compound; and

wherein the compound is removed after the substitution/absorptiontreatment; the conductive film is worked to selectively leave theconductive film in the interiors of the contact hole and the wiringgroove, whereby forming a plug comprising the conductive film in thecontact hole as well as a wiring comprising the conductive film in thewiring groove; then the conductive film is heat-treated at a temperaturewhich is higher than that of solid solution limit at the solid solutionconcentration of constituent material of the absorption layer remainedin the conductive film and which is lower than thesubstitution/absorption treatment temperature, after which theconductive film is annealed, whereby discharging the constituentmaterial of the absorption layer remained in the conductive film to bedischarged out of the conductive film; and a reaction product layercontaining the constituent material of the absorption layer that hasbeen discharged on the surface of the conductive film is removed.

Followings are a specific embodiment of the aforementioned methods [42],[43] and [45] of manufacturing a semiconductor device.

(a) The reaction product layer is removed by means of an RIE etch-backmethod or a CMP method.

[46] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of:

filling a contact hole and/or a wiring groove with a conductive filmthrough a substitution/absorption treatment, the substitution/absorptiontreatment being performed by substituting the conductive film for asubstitutive film in the contact hole and/or the wiring groove, theconductive film being formed in advance on the substitutive film, and byrendering the substitutive film to be absorbed by an absorption layer toform a compound; and

wherein the conductive film is formed on the substitutive film to such athickness which is sufficient enough to reduce the quantity ofconstituent material of the absorption layer diffusing into the interiorof the contact hole and wiring groove at the occasion of thesubstitution/absorption treatment.

[47] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed with a conductive film through asubstitution between a substitutive film and the conductive film formedon the substitutive film, and which is featured to include the steps of:

forming the substitutive film in the interiors of the contact hole andthe wiring groove;

forming the conductive film in a region comprising the contact hole andthe wiring groove;

forming an absorption layer on the conductive film;

forming a film on the absorption layer, which is capable of giving acompressive stress in conformity with a tensile stress in the directionof the conductive film due to a voluminal change of the absorptionlayer;

substituting the conductive film for the substitutive film and allowingthe substitutive film to be absorbed by the absorption layer under aheat treatment; and

removing the substitutive film and absorption layer disposed higher thanthe wiring groove, whereby forming a plug comprising the conductive filmin the contact hole as well as a wiring comprising the conductive filmin the wiring groove.

[48] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed with a conductive film through asubstitution between a substitutive film and the conductive film formedon the substitutive film, and which is featured to include the steps of:

forming the substitutive film in the interiors of the contact hole andthe wiring groove;

forming the conductive film in a region comprising the contact hole andthe wiring groove;

forming a film in the conductive film, which enables the constituentelements of the substitutive film and conductive film to passtherethrough and is capable of alleviating a tensile stress in thedirection of the conductive film due to a voluminal change of theabsorption layer;

forming an absorption layer on the conductive film;

substituting the conductive film for the substitutive film and allowingthe substitutive film to be absorbed by the absorption layer under aheat treatment; and

removing the substitutive film and absorption layer disposed higher thanthe wiring groove, whereby forming a plug comprising the conductive filmin the contact hole as well as a wiring comprising the conductive filmin the wiring groove.

[49] This invention further provides; a method of manufacturingsemiconductor device which comprises a step of filling a contact holeand/or a wiring groove formed with a conductive film through asubstitution between a substitutive film and the conductive film formedon the substitutive film, and which is featured to include the steps of:

forming the substitutive film in the interiors of the contact hole andthe wiring groove;

forming the conductive film in a region comprising the contact hole andthe wiring groove;

forming an absorption film which exhibits little change or shrinkage involume in a heat treatment for substitution where the substitutive filmis tendered to be absorbed by the absorption film;

substituting the conductive film for the substitutive film and allowingthe substitutive film to be absorbed by the absorption layer under aheat treatment; and

removing the substitutive film and absorption layer disposed higher thanthe wiring groove, whereby forming a plug comprising the conductive filmin the contact hole as well as a wiring comprising the conductive filmin the wiring groove.

In the aforementioned method of manufacturing a semiconductor device,the constituent material of the conductive film may be selected from Aland an Al alloy; the constituent material of the substitutive film maybe selected from Si and Ge; and the constituent material of theabsorption layer may be selected from Ti, Hf, V, Zr, W, Co, Ni, Pd andFe.

[50] This invention further provides; a semiconductor device whichcomprises:

a semiconductor substrate;

an insulating film formed on the substrate and having a recessedportion; and

a conductive film formed in the recessed portion;

the conductive film containing a trace amount of a substance having alower melting point than that of element mainly constituting theconductive film.

[51] This invention further provides; a semiconductor device whichcomprises:

a semiconductor substrate;

an insulating film formed on the substrate and having a recessedportion;

a thin film formed at least partially on an inner surface of therecessed portion and consisting of a barrier metal or a materialexhibiting a higher surface energy than that of the insulating film; and

a conductive film formed in the recessed portion;

the conductive film containing a substance having a lower melting pointthan that of element mainly constituting the conductive film, a quantityof the substance being not more than a maximum concentration thereofthat can be solid-solubilized.

Followings are specific embodiments of the aforementioned semiconductordevices [50] and [51].

(a) The maximum concentration of the substance that can besolid-solubilized is selected such that, when the element mainlyconstituting the conductive film and the lower melting point substanceare in a state of solid-liquid equilibrium, it corresponds to a maximumconcentration of the lower melting point substance in the solid phaseconsisting of the element and the lower melting point substance which isequilibrated with the liquid phase.

(b) The element mainly constituting the conductive film and thesubstance having a lower melting point than that of element mainlyconstituting the conductive film are capable of forming an eutectic.

(c) The element mainly constituting the conductive film is at least oneelement selected from the group consisting of Al, Cu, Ag, W, Si, Ge andSiGe.

(d) The substance having a lower melting point than that of elementmainly constituting the conductive film (hereinafter referred to as alower melting point substance) is at least one element selected from thegroup consisting of Sn, Ga, Hg and Ge, if the element mainlyconstituting the conductive film is Al; the lower melting pointsubstance is Bi, if the element mainly constituting the conductive filmis Cu; the lower melting point substance is Tl, if the element mainlyconstituting the conductive film is Ag; the lower melting pointsubstance is at least one element selected from the group consisting ofGe, Ga, Bi, Sn and Ce, if the element mainly constituting the conductivefilm is W; the lower melting point substance is at least one elementselected from the group consisting of Zn, In, Cd, Zg, Sn and Al, if theelement mainly constituting the conductive film is Si, Ge or SiGe.

[52] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate;

forming a recessed portion in the insulating film;

forming a liquid phase containing a conductive element and a substancehaving a lower melting point than that of the conductive element in therecessed portion;

forming a conductive film at least in the recessed portion by shiftingthe composition of the liquid phase from an equilibrium composition to acomposition where the conductive element is excessive, therebyprecipitating the conductive element; and

removing all of materials from the surface of the insulating filmexcluding those formed on the recessed portion.

[53] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate;

forming a recessed portion in the insulating film;

forming a barrier metal or a material exhibiting a higher surface energythan that of the insulating film

forming a liquid phase containing a conductive element and a substancehaving a lower melting point than that of the conductive element in theinsulating film;

forming a conductive film at least in the recessed portion by shiftingthe composition of the liquid phase from an equilibrium composition to acomposition where the conductive element is excessive, therebyprecipitating the conductive element; and

removing all of materials from the surface of the insulating filmexcluding those formed on the recessed portion.

Followings are specific embodiments of the aforementioned methods [52]and [53] of manufacturing a semiconductor device.

(a) The step of forming a liquid phase containing a conductive elementand a substance having a lower melting point than that of the conductiveelement in the recessed portion is performed in such a manner that asolid phase alloy layer containing the conductive element and thesubstance having a lower melting point than that of the conductiveelement is formed in the recessed portion, and then the solid phasealloy layer is heated to melt.

(b) The step of forming a liquid phase containing a conductive elementand a substance having a lower melting point than that of the conductiveelement in the recessed portion is performed in such a manner that alayer of the substance having a lower melting point than that of theconductive element is formed at least in the recessed portion, a layerof the conductive element is formed at least in the recessed portion,and then the layer of the substance having a lower melting point isheated to form a melt, thereby allowing the conductive element to bediffused in the melt.

(c) The step of forming a liquid phase containing a conductive elementand a substance having a lower melting point than that of the conductiveelement in the recessed portion is performed in such a manner that alayer of the substance having a lower melting point than that of theconductive element is formed at least in the recessed portion, and thenthe layer of the substance having a lower melting point is heated toform a liquid phase, into which the conductive element to introduced.

(d) The step of forming a liquid phase containing a conductive elementand a substance having a lower melting point than that of the conductiveelement in the recessed portion is performed in such a manner that amelt of the substance having a lower melting point than that of theconductive element, or a melt consisting of the conductive element andthe substance having a lower melting point is forced to fill in therecessed portion under pressure.

(e) The step of shifting the composition of the liquid phase from anequilibrium composition to a composition where the conductive element isexcessive thereby to precipitate the conductive element is performed insuch a manner that a process of lowering the temperature of the liquidphase, or a process of lowering the temperature of the liquid phase to asolid-liquid two-phase temperature region and maintaining thistemperature is performed at least once.

(f) The step of shifting the composition of the liquid phase from anequilibrium composition to a composition where the conductive element isexcessive thereby to precipitate the conductive element comprises thesub-steps of; lowering the temperature of the liquid phase to asolid-liquid two-phase temperature region, maintaining this temperaturethereby allowing the conductive element to precipitate; increasing thetemperature of the phase to restore the liquid phase; introducing theconductive element into the liquid phase; and lowering the liquid phase;the sub-steps being performed at least once.

(g) The step of shifting the composition of the liquid phase from anequilibrium composition to a composition where the conductive element isexcessive thereby to precipitate the conductive element includes a stepof heat treatment in an atmosphere containing at least one elementselected from the group consisting of N, O and H.

(h) The step of shifting the composition of the liquid phase from anequilibrium composition to a composition where the conductive element isexcessive thereby to precipitate the conductive element includes a stepof heat treatment in an atmosphere enabling a formation of a gas phasecompound containing the substance having a lower melting point, and astep of removing the gas phase compound.

(i) The step of removing all of materials from the surface of theinsulating film excluding those formed on the recessed portion comprisesthe sub-steps of; introducing a gas containing a halogen to form ahalide; and removing the halide.

(j) The step of removing all of materials from the surface of theinsulating film excluding those formed on the recessed portion comprisesthe sub-steps of; introducing a gas containing at least one elementselected from chlorine, fluorine, iodine and bromine to form a chloride,fluoride, iodide or bromide; and removing the halide.

[54] This invention further provides; a method of manufacturingsemiconductor device which comprises the steps of:

forming an insulating film on a semiconductor substrate;

forming a recessed portion in the insulating film;

forming a liquid phase containing a conductive element and a substancehaving a lower melting point than that of the conductive element in therecessed portion;

forming a conductive film in the recessed portion by shifting thecomposition of the liquid phase from an equilibrium composition to acomposition where the conductive element is excessive, therebyprecipitating the conductive element; and

removing all of materials from the surface of the insulating filmexcluding those formed on the recessed portion;

an additive element is introduced into the conductive element during orafter the precipitation of the conductive element.

Followings are specific embodiments of the aforementioned method [54] ofmanufacturing a semiconductor device.

(a) The conductive element is formed of a single kind of element.

(b) The additive element is an element which is capable of improving theelectromigration resistance or stress migration resistance of theconductive film after the precipitation.

(c) The additive element is an element which is capable of lowering thesolid solution limit of the substance having a lower melting point afterthe precipitation.

Additional object and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIGS. 1A and 1B illustrate respectively a cross-sectional view of amultilayer wiring structure to be produced according to the conventionalmethod;

FIGS. 2A and 2B show respectively a cross-sectional view of a multilayerwiring structure to be produced according to the conventional method,illustrating problems involved therein;

FIGS. 3A to 3F show respectively a cross-sectional view illustrating themanufacturing steps of the semiconductor device of Example 1;

FIG. 4 is a partially cross-sectioned perspective view illustrating astructure in the middle of the manufacturing steps of the semiconductordevice of Example 1;

FIGS. 5A and 5B show respectively a cross-sectional view illustratingproblems involved when wiring grooves of various widths are existed;

FIGS. 6A and 6B show respectively a cross-sectional view illustratinghow to solve the problems involved when wiring grooves of various widthsare existed;

FIGS. 7A to 7C show respectively a cross-sectional view illustrating thequantity of Si to be left in the wiring groove and contact hole;

FIGS. 8A to 8F show respectively a cross-sectional view of various kindsof dual damascene wiring structure which differ from each other inlocation of a barrier film;

FIGS. 9A and 9B show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to amodified example of Example 1;

FIGS. 10A to 10F show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example2;

FIGS. 11A to 11E show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example3;

FIGS. 12A to 12E show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example4;

FIGS. 13A to 13F show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example5;

FIGS. 14A to 14D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example10;

FIGS. 15A to 15H show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example11;

FIGS. 16A to 16J show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example12;

FIGS. 17A to 17E show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to amodified embodiment of Example 12;

FIGS. 18A to 18D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example13;

FIGS. 19A to 19C show respectively a graph illustrating the temperaturesequence of heat treatment;

FIGS. 20A to 20F show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example16;

FIGS. 21A to 21D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example17;

FIGS. 22A to 22E show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example18;

FIGS. 23A to 23D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example20;

FIGS. 24A to 24D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example22;

FIGS. 25A to 25C show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example23;

FIGS. 26A to 26D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example24;

FIGS. 27A to 27D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example25;

FIGS. 28A to 28H show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example26;

FIGS. 29A to 29J show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example27;

FIG. 30 shows a graph illustrating a relationship between the depositionrate of B-containing a-Si film and B-free a-Si film and the temperaturethereof;

FIG. 31 shows a graph illustrating a cause for a difference in specificresistance of an Al film after the deposition thereof, which has beenarisen depending on the kinds of Si film employed as a substitutivefilm;

FIG. 32 shows a graph separately illustrating the factors for specificresistance;

FIGS. 33A to 33D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example30;

FIGS. 34A to 34D show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to amodified embodiment of Example 30;

FIG. 35 shows a cross-sectional view illustrating the manufacturingsteps of the semiconductor device according to a modified embodiment ofExample 29;

FIGS. 36A and 36B show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to amodified embodiment of Example 29;

FIG. 37 shows a graph illustrating a relationship between thetemperature of substitution heat treatment and the yield of a Ticompound;

FIGS. 38A and 38B show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example33;

FIGS. 39A to 39C show respectively a cross-sectional view illustratingthe manufacturing steps of the semiconductor device according to Example34;

FIGS. 40A to 40E show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 35;

FIGS. 41A to 41E show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 36;

FIGS. 42A to 42E show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 38;

FIGS. 43A to 43E show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 39;

FIGS. 44A to 44E show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according to amodified embodiment of Example 39;

FIGS. 45A to 45E show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 40;

FIGS. 46A to 46G show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 42;

FIGS. 47A to 47C show respectively a cross-sectional view illustratingthe steps of applying a uniaxial stress according to Example 40;

FIGS. 48A to 48D show respectively a cross-sectional view illustratingthe steps of a liquid phase filling method employing a uniaxial stressaccording to Example 44;

FIGS. 49A to 49C show respectively a cross-sectional view illustratingthe method of modifying the surface of oxide film according to Example46;

FIGS. 50A to 50C show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 47;

FIG. 51 shows a graph illustrating a phase diagram of Al—Sn;

FIGS. 52A and 52B show respectively a schematic view illustrating thedeposition and heating steps of an Al—Sn film and an Sn film accordingto Example 50;

FIGS. 53A to 53D show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 52;

FIGS. 54A to 54D show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according to amodified embodiment of Example 54; and

FIGS. 55A to 55C show respectively a cross-sectional view illustratingthe method of forming a connecting plug and groove wiring according toExample 55.

DETAILED DESCRIPTION OF THE INVENTION

According to a first aspect of this invention, there is provided astructure provided with a contact hole and a wiring groove which isfeatured in that the interiors of the contact hole and wiring groove areincompletely filled with a substitutive film (a film to be substituted).

In this invention, as a method of filling a recessed portion of highaspect ratio, a method of substituting a conductive film for asubstitutive film after the deposition of this substitutive film isemployed. In this case, it is preferable to employ a deposition methodwhich is excellent in step coverage for the formation of thesubstitutive film.

If only the bottom portion of the contact hole is filled with thesubstitutive film in this case, the aspect ratio of the recessedportion, i.e. the contact hole and wiring groove to be filled with aconductive film can be reduced, so that, if the aspect ratio of therecessed portion is reduced in this manner, the conventional fillingtechnique, e.g. a co-use of sputtering and reflow can employed forfilling the recessed portion.

Generally, the aspect ratio of wiring (thickness of wiring/width ofwiring) to be employed for an LSI does not exceed over 1. Moreover, asfar as the longitudinal direction of the wiring groove is concerned,even if the incident angle of the sputtering particles (the anglebetween the direction normal to the substrate and the moving directionof particles) is relatively large, the influence of shadowing can beavoided, so that it is possible to easily fill the wiring groove even ifa deposition method which is high in throughput but low in directivity,such as the ordinary sputtering method, is employed.

Since the quantity of the substitutive film can be minimized, anincrease in wire resistance due to the constituent material of thesubstitutive film remaining in a conductive film can be inhibited.Furthermore, the time for substitution can be saved, and the temperaturefor the substitution can be lowered, thus expanding the process marginand process window.

A second aspect of this invention is featured in the location of forminga barrier film.

For example, the barrier film on the inner surface of wiring groove iseffective, in addition to its inherent properties of preventing areaction and diffusion, in improving the reliability of wiring. If anelectromigration is caused to occur when electric current is passedthrough a wiring, or if stress migration is caused to occur due to astress from the peripheral materials, a large number of voids andhillock would be generated in the wiring. However, if a barrier film isformed in advance around a wiring, the electric current would be allowedto continue to flow through the barrier film, thus preventing thedisconnection of wiring.

Moreover, the barrier film functions, depending on the material thereof,to reduce a native oxide film formed on the surface of a conductivelayer such as a lower wiring. For example, when a barrier film is formedon a conductive layer formed on the bottom of contact hole, it becomespossible to directly (without intervened by a native oxide film)electrically connect the plug with the conductive layer, thus decreasingthe contact resistance.

On the other hand, if the plug and the wiring are formed of the samematerial, there would be no diffusion barrier to migration, wherebymaking it possible to improve the reliability of the device. As for theimprovement of EM resistance and SM resistance, or for the lowering ofresistance, any appropriate structure can be adopted according to theend-use.

A third aspect of this invention is featured in the employment of thesubstitutive film as a film for improving the wettability at theoccasion of filling with a conductive film, superfluous substitutivefilm being removed after the filling of conductive film is finished.

For example, in the method of filling a conductive film by making use ofa combination of sputtering method and reflow method, the wettability ofthe inner surfaces of contact hole and wiring groove gives muchinfluence to the filling property of conductive film. A film forimproving wettability is called liner in the technique of reflow, and acontact hole or a wiring groove of high aspect ratio is required to beslightly covered with this liner.

As hereinafter explained with reference to the specific embodiments, anSi film which is capable of easily covering a recessed portion of highaspect ratio exhibits an excellent wettability to an Al film, so that itis suited for use as a liner material.

Since the liner also functions a diffusion barrier to migration, theliner should preferably be removed after it is employed for filling aconductive film. Moreover, since the liner formed on the inner surfaceof wiring groove leads to a substantial reduction in volume of lowresistant conductive film and hence an increase of wire resistance, itis desirable, in this respect too, to remove the liner.

In view of this, a method of causing the liner (substitutive film) andthe conductive film to undergo a mutual diffusion or a substitution, andrendering the liner to be absorbed by an absorption layer in a separateregion thereby to remove the liner is effective.

A fourth aspect of this invention is featured in the employment of asubstitution/absorption treatment which is performed after a nativeoxide film or impurities attached to the surface of the substitutivefilm are removed.

The native oxide film or impurities attached to the surface of thesubstitutive film obstruct the mutual diffusion between the substitutivefilm and the conductive film, thus prolonging the substitution time, andas a result, the substitution between the substitutive film and theconductive film as well as the absorption of the substitutive film bythe absorption film may become insufficient, thus increasing the wireresistance.

As a method for preventing the increase of wire resistance due to thepresence of native oxide film or impurities, it is conceivable to employvarious methods, such as a method of removing the native oxide film,etc., a method of preventing the generation of the native oxide film,etc., a method of decomposing the native oxide film, etc. Since thesteps to be performed before and after this method as well as thetransferring system of substrate (sheet system or batch system) are alsorelated to this method, these methods should be suitably selected takingthe specific processes into consideration.

A fifth aspect of this invention is featured in the formation of asubstitutive film after a native oxide film or impurities which areattached to the surface of a lower wiring or of a conductive layer areremoved.

When the plug or wiring is to be formed through the substitution of aconductive film as in the case of this invention, it is very importantto perform a cleaning of the surface of the conductive layer in the stepof filling a substitutive film prior to the substitution step. If anative oxide film or impurities, i.e. insulating materials are leftremained on the surface of the conductive layer, the contact resistancebetween the conductive layer and the wiring disposed on the conductivelayer would be increased, thus raising a problem.

A sixth aspect of this invention is featured in the acceleration of thesubstitution process by making use of a conductive film having aroughened surface, by performing a heat treatment, or by forming aplurality of absorption bodies.

When a plurality of absorption bodies are formed on the same level ordifferent level (thickness-wise) in a substrate in particular, the areaof interface between the conductive film and the absorption layer can beincreased by minimizing an overlapped portion of each absorption layer.Further, it is important, in view of lowering the wire resistance, toprevent the absorption layer and a reaction product from being leftremained in the contact hole or the wiring groove.

A seventh aspect of this invention is featured in the process ofsuppressing an increase in resistance of the conductive film, whereinthe substitutive film is substituted by the conductive film under a heattreatment, whereby filling the contact hole or wiring groove with theconductive film, and at the same time, the substitutive film thussubstituted is allowed to be absorbed by the absorption layer.

The quantity of the constituent material of the substitutive film to besolid-solubilized in the conductive film at the occasion of heattreatment is determined depending on the temperature of the heattreatment. Therefore, a multi-heat treatment is employed in thisinvention as the aforementioned heat treatment, i.e. a heat treatmentwherein the temperature is changed from a higher temperature to a lowertemperature, and a heat treatment wherein temperature is decreasedgradually after heat treatment.

Namely, the aforementioned substitution, filling and absorption areperformed in a high temperature heat treatment (preferably, a hightemperature heat treatment of short time), and then the temperature islowered so as to lower the solid solution limit of the constituentmaterial of the substitutive film in the conductive film.

As a result, the constituent material of the substitutive film which issolid-solubilized in the conductive film in the aforementioned hightemperature heat treatment is allowed to be discharged out of theconductive film until the solid solution limit corresponding to thelowered temperature is taken place. Accordingly, the quantity of theconstituent material of the substitutive film in the conductive film issufficiently minimized, thus effectively suppressing an increase ofresistance of the conductive film. Through this simply heat treatment, awiring exhibiting a low resistance which is substantially equivalent tothe inherent resistance of the conductive film can be obtained.

An eighth aspect of this invention is featured in the process of furthersuppressing an increase in wire resistance, wherein the constituentmaterial of the substitutive film, which is still remained in the plugor wiring which has been formed through the aforementionedsubstitution/absorption treatment is re-absorbed in a heated conditionby an additional absorption layer which has been newly formed on thesurface of the contact hole or wiring groove.

Further, when a conductive layer such as a lower wiring is formed by thesubstitution/absorption of the conductive film, it is possible to allowthe constituent material of the substitutive film remaining in theconductive layer to be re-absorbed in the absorption layer via the plugin the contact hole at the occasion of heat treatment wherein thesubstitutive film is substituted by the conductive film and at the sametime, the substitutive film is absorbed by the absorption layer.

A ninth aspect of this invention is featured in that, for the purpose ofimproving the reliability or for the purpose of lowering the wireresistance, an element (additive element) which is different from theconstituent material of the substitutive film or of the absorption layeris added in the conductive film during or after thesubstitution/absorption treatment.

If this additive element is added to the conductive film in advance, theadditive element may be reacted with the constituent material of thesubstitutive film or of the absorption layer during thesubstitution/absorption treatment. If such is the case, a conductivefilm consisting of a single element is employed in thesubstitution/absorption treatment, and then the additive element isadded to the conductive film as proposed by this invention.

Although the constituent material of the substitutive film is stillincluded in the conductive film during or after thesubstitution/absorption treatment, if this additive element is added tothe conductive film, the solid solution limit of the constituentmaterial of the substitutive film might be lowered, thus furtherreducing the resistance of the conductive film. In this case, acombination of materials wherein the additive element is allowed toreact with the conductive film thereby to greatly increase theresistance thereof should be avoided.

A tenth aspect of this invention is featured in that the diffusion rateof the constituent material of the substitutive film inside theconductive film is made faster than that of the constituent material ofthe absorption layer.

Only when the aforementioned relationship is met, it is possible toallow the substitutive film (which is located at the place where aconductive film is intended to be filled) to diffuse in the directiontoward the absorption layer and to be absorbed by the absorption layer.

When the constituent material of the substitutive film is absorbed bythe absorption layer, i.e. when a compound is formed as a result, thiscompound functions sometimes as a barrier layer to inhibit the diffusionof the absorption layer into the conductive film or to inhibit thereaction between the absorption layer and the conductive film.Therefore, it is possible to employ a barrier film meeting theaforementioned relationship regarding the diffusion rate and having theaforementioned function and to interpose it between the absorption layerand the conductive film.

An eleventh aspect of this invention is featured in that although thefilling of conductive film is performed through a substitution betweenthe conductive film and the substitutive film, the absorption layer isnot employed. Namely, according to this invention, the conductive filmis substituted for the substitutive film, and at the same time, thesubstitutive film thus substituted by the conductive film is allowed toprecipitate on the surface of the conductive film, the precipitatedsubstitutive film being subsequently left as it is or removed if it isno more necessary.

If the combination between the conductive film and the substitutive filmis suitably selected, the constituent material of the substitutive filmor the compound thereof can be easily precipitated on the surface of theconductive film by heat-treating the conductive film and thesubstitutive film in a vacuum or in a gaseous atmosphere. Therefore, itis possible according to this invention to dispense with the absorptionlayer, so that the filling process of the conductive film can besimplified by taking advantage of the substitution between theconductive film and the substitutive film.

Further, if a material which is capable of forming a compound gas in agaseous atmosphere is selected as a constituent material of thesubstitutive film, and then the heat treatment is performed in thegaseous atmosphere, the substitutive film precipitated on the surface ofthe conductive film can be removed in the form of the compound gas, sothat the subsequent step of removing the substitutive film can besimplified.

A twelfth aspect of this invention is featured in that the substitutivefilms in the contact hole and wiring groove each formed in theinsulating film of each layer are concurrently substituted by theconductive film in a single heat treatment, so that the process can besimplified extremely.

Further, if a material having a high melting point is selected as aconstituent material of the substitutive film, there is no possibilityof being deformed under the influence of heat in contrast to a lowmelting point metal such as Al, an insulating film which is high infilm-forming temperature can be employed.

Since an insulating film which is high in film-forming temperature isrelatively free from impurities such as water, it is possible to improvethe current leak property, thus improving the reliability of the device.If the substitution by the conductive film is to be effected en bloc, aheat treatment at a higher temperature can be performed since it doesnot include, as an underlying layer, a low melting point material suchas Al which may raise a problem of deformation, thus saving thesubstitution time even if the quantity of the substitutive film isrelatively large.

According to thirteenth aspect of this invention, it is possible toeasily manufacture a structure which is featured in that the interior ofthe contact hole is filled with a plug consisting of a high meltingpoint metal, and that the plug is contacted at the upper surface of thewiring with a high melting point conductive film containing a meltingpoint metal.

It is possible, with this structure, to continue to pass electriccurrent to the plug via the high melting point conductive film formed onthe upper surface of the wiring even if a void due to anelectromigration or a stress migration is generated in the wiring, thusimproving the reliability of the device. Furthermore, when the plug isprotruded into the wiring groove, the contact area with the wiring canbe increased, thus lowering the contact resistance.

A fourteenth aspect of this invention is featured in that, after thesubstitution between the substitutive film and the conductive film aswell as the absorption of the substitutive film by the absorption layerare performed, a superfluous absorption layer, the compound formed as aresult of the absorption, and a superfluous conductive film which areleft outside the wiring groove are successively removed.

An abrasion en bloc of a laminate film consisting of different kinds ofmaterial by means of the CMP method requires a combination of variousabrasives and abrasive cloths, thus complicating the process. However,it is possible to perform the CMP process by a single step bywet-etching or dry-etching the upper layer portion of the laminate filmas suggested by this invention, thereby making it possible to simplifythe process.

A fifteenth aspect of this invention is featured in that, thesubstitutive film contains a diffusion-promoting material or adiffusion-inhibiting material. It is possible, through the inclusion ofthe diffusion-promoting material in the substitutive film, to promotethe mutual diffusion between the substitutive film and the conductivefilm. On the other hand, it is possible, through the inclusion of thediffusion-inhibiting material in the substitutive film, to inhibit thediffusion of the absorption film into the conductive film.

A sixteenth aspect of this invention is featured in that the diffusionof the constituent material of the absorption layer into the conductivefilm is inhibited. As a result, an increase in resistance of theconductive film due to the diffusion of the constituent material of theabsorption layer into the conductive film can be prevented.

A seventeenth aspect of this invention is featured in that a film whichis capable of giving a compressive stress in conformity with a tensilestress in the direction of the conductive film, a layer for alleviatingthe tensile stress or a shrinkable absorption film is formed. As aresult, it is possible to inhibit the formation of void in theconductive film.

The principle of an eighteenth aspect of this invention resides in afilling technique for a contact hole of high aspect ratio, whichcomprises a process of forming a precipitation seed layer by making useof a solid-liquid reaction, thereby to grow a conductive material.

The eighteenth aspect of this invention is related to a process offorming a wiring/electrode material of a semiconductor device such asFET on the surface of substrate or in the contact hole, wiring groove orother recessed portion in the vicinity of an element; wherein an alloycomprising a wiring/electrode material and a material having a lowermelting point than that of the material and capable of forming a simpleeutectic, a single-layer film constituted by the alloy, or a laminatefilm constituted by the alloy is deposited at least in the recessedportions, (or the low melting point metal is preliminarily deposited atleast in the recessed portion before the alloy is deposited in therecessed portion); and, after the substrate is heated to obtain a liquidphase in the vicinity of desired process temperature, thewiring/electrode material is allowed to precipitate; by cooling theliquid phase; by selectively removing the low melting point metal; or bysupplying the wiring/electrode material to the liquid phase wherebyallowing a portion of the wiring/electrode material to be precipitatedout of the equilibrium composition of the initial liquid phase; theprecipitated wiring/electrode material being utilized as a seed phase,whereby forming the wiring/electrode material on the surface of thesubstrate or in the recessed portions.

In this case, the composition of molten alloy before the precipitationof wiring/electrode material may be those which enables a liquid phaseto be obtained at a temperature lower than the upper limit of thedesired process temperature. This temperature enabling a liquid phase tobe obtained may be a temperature which is not lower than the meltingpoint of the single low melting point material constituting the liquidphase and which is higher than that of the eutectic line of a mixtureconsisting of the low melting point material and wiring/electrodematerial constituting the liquid phase.

The eighteenth aspect of this invention is also featured in that thenucleus of wiring/electrode material is preferentially generated at thelocation where a high density of nucleus can be non-uniformly generated,e.g. at the interface between a wiring material and an insulating film,i.e. the surfaces of contact hole and wiring groove, at the bottom ofthe wiring groove, at the edge of the bottom of the contact hole, and atthe surface of an lower wiring, whereby depositing the wiring/electrodematerial on a desired surface or in a desired recessed portion.

Next, the examples according to this invention will be explained withreference to the accompanying drawings.

EXAMPLE 1

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 3A to 3F.

First of all, a first wiring layer 1 is formed on an Si substrate (notshown) provided with an element. This first wiring layer 1 is partiallyseparated from each other via an insulating film 2. Then, an interlayerinsulating film 3 is formed all over the surface of the Si substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole 4, and at the same time a wiringgroove 5 is selectively formed likewise at a region including thiscontact hole 4. Namely, the contact hole 4 connected with the firstwiring layer 1 and the wiring groove 5 are successively formed.

In this example, the wiring groove 5 is also formed at a region wherethe contact hole 4 is not included. Then, a TiN film 6 is formed as abarrier film by means of sputtering method all over the surface of theresultant substrate (FIG. 3A). FIG. 5 illustrates a partiallycross-sectioned perspective view of the substrate at this stage.

Then, an Si film 7 is deposited all over the substrate by means ofLP-CVD method in a manner to avoid the generation of voids in theinterior of the contact hole 4 (FIG. 3B).

When this CVD method is employed, an Si film can be formed in conformitywith the shape of the hole. Accordingly, when the Si film 7 is depositedto a thickness equal to at least a half of the pore diameter of thecontact hole 4, the interior of the contact hole 4 can be completelyfilled with the Si film 7.

Further, when LP-CVD method is employed, it is possible to depositvarious kinds of Si film such as a polycrystalline Si film, an amorphousSi film, a boron doped amorphous Si film, etc. An Si film of any kindscan be employed in this invention. Since the substituting performancesuch as substitution rate of Si film differs from each other dependingon the kinds of the Si film, the Si film should be suitably selectedtaking this difference into consideration.

Further, since the deposition temperature of Si film also differsdepending on the kinds of the Si film, some kinds of Si film may not besuited for use depending on the structure of the underlying layer.

For example, if the first wiring layer 1 is formed of a high meltingpoint metal or alloy such as W and WSi, a polycrystalline Si whichrequires a deposition temperature of about 600° C. may be usable.However, if the first wiring layer 1 is formed of a low melting pointmetal such as Al, the Si film to be used should preferably be confinedto an amorphous Si film or a boron doped amorphous Si film, which can beformed with a deposition temperature of about 350 to 450° C.

Because, when the substrate is heated under the condition where thecontact hole connected to the first wiring layer 1 of a low meltingpoint metal is kept open, the low melting point metal may protrude intothe interior of the contact hole, thus resulting in the generation ofvoid in the wiring portion.

The boron doped amorphous Si film is formed of an Si film which can beproduced from a mixture of Si₂H₆ and B₂H₆. In this case, B₂H₆ iseffective in promoting the decomposition of the Si₂H₆. Therefore, ifboron doped amorphous Si film is employed, the deposition temperature ofthe Si film can be easily lowered.

Then, the Si film 7 is partially etched away by means of CDE employingCF₄ gas in such a manner that at least the portion of the Si film 7which is disposed inside the contact hole 4 is left remained therein.(FIG. 3C).

The CDE is an etching method wherein a gas containing halogen such a CF₄is decomposed by means of microwave discharge thereby to form an activehalogen radical such as F* (F radical), which is then introduced towardthe surface of the substrate so as to isotropically etch the layer to beetched.

When the Si film 7 that has been deposited by means of CVD is etched toa depth corresponding to the deposited thickness by making use of CDE,the Si film 7 that has been deposited on the surface excluding thatfilled in the interior of the contact hole 4 can be removed.

Furthermore, the etching rate of Si by the F radical can be accelerated,through adjustment of etching condition, 50 times faster than theetching rate of TiN or SiO₂, thus making it possible to avoid anydeformation of wiring grooves. It is also possible to remove the Si film7 by making use of the RIE etch-back method.

Depending on the layout of pattern, the quantity of Si film 7 may becomelarge. In this case, the post heat treatment for substituting the Alfilm for the Si film 7 may be prolonged. Therefore, the quantity of Sifilm to be left in the wiring groove and contact hole should preferablybe adjusted as shown in FIGS. 7A to 7C.

In the foregoing explanation of this example, the Si film 7 is depositedall over the surface of the substrate, and then the Si film 7 is etchedaway in such a manner that only the portion of Si film 7 that has beenfilled in the contact hole is left remained in the contact hole.However, it is also possible to selectively fill the contact hole withSi film by means of a selective CVD method or any other methods. Whenthe selective CVD method is employed, the removal of Si film in asubsequent step is no more required, thus making it possible to minimizethe number of the manufacturing step.

Further, it is also possible to employ another process wherein all of Sifilm 7 except those filled in the contact holes 4 and wiring grooves 5is removed by means of the CMP method, and then the Si film 7 filled inthe wiring grooves 5 is removed by means. of the CDE etch-back method orthe RIE etch-back method, thus leaving only the interior of the contacthole 4 filled with the Si film 7.

The reason for not performing the CDE etch-back method or the RIEetch-back method immediately after the deposition of the Si film 7 is asfollows. Namely, when a wiring groove 5 differing in width from the restof the wiring groove 5 is existed as shown in FIG. 5A, even though theSi film 7 which has been filled in a wiring groove 5 of relatively widewidth can be removed by the etch-back of the film to an extent thatcorresponds to the deposited thickness of the Si film 7, the Si film 7which has been fully filled in a wiring groove 5 of relatively narrowwidth cannot be completely removed, thus leaving a portion thereof inthe wiring groove 5 as shown in FIG. 5B.

Accordingly, in the case of pattern layout where the wiring grooves ofnarrow width are densely formed, the Si may left in large quantity, thusincreasing a possibility that a portion of the Si film 7 that has beenfailed to be absorbed by a Ti film 9 may formed into a nodule. If thereis such a possibility, the Si film should be treated at first by meansof the CMP as mentioned above (FIG. 6A), and then subjected to theetch-back, thus leaving the Si film 7 in the interior of the contacthole 4 (FIG. 6B).

Alternatively, another method may be employed wherein a resist is formedall over a substrate, and then the resist is subjected to an etch-backunder a condition where the etching rate of the resist is adjusted tobecome equal to that of Si film 7, thus leaving the Si film 7 in thesame height throughout the surface of substrate where a plurality of Sifilms are originally disposed at a different level.

Alternatively, when the Si film 7 is deposited to a thickness equal toat least a half of the width of the wiring groove, all of the groovescan be completely filled with the Si film 7, so that the problem ofdifference in surface level of the Si film 7 in the subsequent etch-backstep can be solved.

In this case however, Si is required to be deposited excessively, thusprolonging the deposition time. It can be the generally in the CVD of Sithat under the condition where the deposition rate is determined by thefeeding of raw material, the deposition rate can be accelerated but thestep coverage property becomes poor, and that under the condition wherethe deposition rate is determined by the reaction, the deposition rateis slow but the step coverage property becomes excellent.

In the case of this invention, the interior of the contact hole isrequired to be excellent in step coverage, so that the deposition underthe condition where the reaction rate prevails is desired. However, theSi film is required to be deposited in heavy in order to fill all of therecessed portions including the wiring groove, thus prolonging thedeposition time.

In this case, the deposition of Si may be performed under the conditionwhere the reaction rate prevails in the stage of filling the contacthole, and then under condition where the raw material-feeding rateprevails so as to accelerate the deposition rate in the subsequent stageof increasing the film thickness. By the employment of this method it ispossible to simultaneously realize the improvement of step coverage andthe saving of deposition time. This step-wise film-forming method isuseful in particular where a single-wafer processing type CVD apparatusdealing with a long through-put is to be employed.

Then, the native oxide film and impurities such as F and C on thesurface of the Si film 7 are removed by means of Ar ion sputtering(reverse sputtering) in a vacuum, and then an Al film 8 and a Ti film 9are successively formed on the entire surface of the Si film 7 in avacuum in order to prevent the surface of the Si film 7 from beingreoxidized or soiled (FIG. 3D). This Al film 8 may be a pure Al film oran Al alloy film containing Cu for instance.

The Ar ion sputtering may be performed by making use of a physicaletching wherein a high-frequency power is applied to the substrate togenerate a discharge and the ionized Ar ions are allowed to be pulled bythe self-bias of the substrate whereby etching the aforementioned nativeoxide film and impurities.

The sputtering method for forming the Al film 8 may be performed by theconventional sputtering method. However, since this Al film 8 isrequired to be formed even in the interior of the wiring groove and alsorequired to be excellent in step coverage, it may be advisable to employa directional sputtering method or a reflow method which is acombination of a directional sputtering method and a thermal sputteringmethod.

The formation of Al film 8 and Ti film 9 after the removal of theaforementioned native oxide film and impurities can be performed bymaking use of a cluster tool for instance. This cluster tool is acomposite apparatus provided with a wafer-transferring mechanism withwhich a substrate (wafer) can be transferred between a plurality ofvacuum chambers, so that it is possible with this cluster tool tocontinuously perform the removal of the natural oxidation film and theprocess of sputtering in a vacuum without exposing the substrate to theexternal atmosphere.

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilm 8 and at the same time allowing a silicide-forming reaction to takeplace between the Si film 7 and the Ti film 9. Through the formation ofthe silicide, the Si film 7 is absorbed by the Ti film 9 (FIG. 3E).

In FIG. 3E, the reference numeral 10 represents an excessive portion ofTi film 9 which is not employed for the formation of the silicifyingreaction and the aforementioned Ti silicide (hereinafter referred to asa Ti/Ti silicide film). In this Ti/Ti silicide film, the region thereoffacing the Al film 8 is predominantly occupied by the Ti silicide filmwhile the surface region is predominantly occupied by the Ti film.

The heat treatment in this case may be performed by making use of eithera single-wafer processing type or a batch type heat treatment apparatus.

Finally, the Ti/Ti silicide film and any excessive Al film 8 are removedby means of the CMP method. In this occasion, the TiN film 6 employed asa barrier film and disposed on the upper portion of the substrate isconcurrently removed (FIG. 3F). As a result, an Al plug and an Al wiringlayer (a second wiring layer) both consisting of the Al film 8 areformed in the interiors of the contact hole 4 and the wiring groove 5,respectively.

In the explanation of this example, the Si film 7, the Al film 8 and theTi film 9 are employed as a film to be substituted, a conductive filmand an absorption film, respectively. In this case, the Al film 8 issubstituted for the Si film 7, and the Si film 7 is absorbed by theupper Ti film 9 through a silicifying reaction between the Si film 7 andthe Ti film 9.

This phenomenon can be explained as follows. Namely, an inter-diffusionis caused to take place between the Si film 7 and the Al film 8, and theSi atoms diffused into the Al film 8 are then allowed to pass throughthe Al film 8 to reach the Ti film 9, whereby causing a silicifyingreaction to take place. Because of this silicifying reaction, theconcentration of Si at the boundary region of the Al film 8. with the Tifilm 9 is caused to diminish, thus generating a concentration gradientof Si. As a result, Si atoms are forced to further diffuse toward the Tifilm 9 to be absorbed by the Ti film 9.

Since the Si film 7 filled in the interior of the wiring groove isremoved by means of the CDE etch-back in this example, the quantity ofSi film 7 (quantity of. Si) to be substituted by the Al film 8 isminimized, so that the heat treatment time for the substitution can besubstantially shortened.

Moreover, since the quantity of Si in the Al film 8 is relatively smallat the portion of the wiring groove 5 locating remote from the contacthole 4, the electric resistivity of the wiring layer can be lowered as awhole.

Since the quantity of Si can be minimized as mentioned above, the filmthickness of the Ti film 9 functioning as an absorbent can be alsominimized, and hence the thickness of Ti silicide to be produced wouldbecome thinner so that the time required for removing the Ti/Ti silicidefilm can be shortened.

Furthermore, since the quantity of Si can be minimized as mentionedabove, it is possible to suppress the generation of Si nodules, andhence to suppress an increase in electric resistance resulting from theformation of the Si nodules. Further, since it is possible to suppressthe generation of Si nodules, the generation of scratch due to the Sinodules in the step of removing the Si nodules by means of the CMPmethod can be prevented.

According to this example, a barrier film 6 is formed after theformation of the contact holes 4 and the wiring grooves 5, wherebyforming a structure where the entire inner surfaces of the contact holesand the wiring grooves are covered by the barrier film 6. However, it isalso possible to adopt another structure as shown in FIGS. 8A to 8F.

For example, if the barrier film 6 is formed by means of a sputteringmethod which is low in coverage property in the step of forming thebarrier film 6 after the formation of the contact holes 4 and the wiringgrooves 5, a wiring structure where no barrier film 6 is deposited onthe bottom of the contact hole 4 can be obtained (FIG. 8A).

In the case where the first wiring layer 1 is formed of an Al wiringlayer, the presence of the barrier film 6 on the bottom of the contacthole 4 becomes an obstacle for the diffusion of electromigration (EM),thus inviting the discontinuity of diffusion rate and hence a cause forthe deterioration of the EM resistance.

By contrast, the barrier film 6 deposited on the side walls of thewiring groove 5 functions also as a compensating lead wire allowingelectric current to pass therethrough when a void is generated due tothe EM in the wiring portion. Therefore, when the structure shown inFIG. 8A is adopted, the reliability of the bottom of the contact hole 4and the wiring portion can be improved.

On the contrary, when the first wiring layer 1 is formed of a W wiringlayer, the presence of barrier 6 is required for the purpose ofsuppressing the reaction between the W wiring layer and the Al film 8.In this case, a sputtering method excellent in directivity or a CVDmethod excellent step coverage can be employed after the formation ofboth contact hole 4 and wiring layer 5, whereby forming the barrier film6 even on the bottom of the contact hole 4 (FIG. 8B).

Alternatively, if the barrier film 6 is formed after the formation ofthe contact hole 4 and then the wiring groove 5 is formed, it ispossible to form the barrier film 6 only on the inner surface of thecontact hole 4 (FIG. 8C). Further, if the barrier film 6 is formed afterthe formation of the wiring groove 5 and then the contact hole 4 isformed, it is possible to form the barrier film 6 only on the innersurface of the wiring groove 5 without depositing the barrier film 6 onthe inner surface of the contact hole 4 (FIG. 8D).

Further, if the wiring groove 5 and contact hole 4 are formed after theformation of barrier film 6, it is possible to form the barrier film 6on the region other than the wiring groove 5 and contact hole 4 (FIG.8E). In this case, an insulating material is employed for the barrierfilm 6.

It is also possible to form the barrier film 6 only on the upper surfaceof the wiring layer. For example, as shown in FIG. 8F, the wiring groove5 is filled with the Al film 8 at first and then the superfluousportions of the Al film 8 and Ti/Ti silicide film are remove by means ofthe CMP taking a long polishing time of the CMP. As a result, astructure where the upper surface of the Al film 8 functioning as awiring layer is lowered than the upper surface of the interlayerinsulating film 3 due to the phenomenon of dishing can be obtained.

After the barrier film 6 is formed all over the surface of the resultantstructure, the barrier film 6 is etched to an extent to leave thebarrier film 6 only on the upper surface of the wiring layer. It is alsopossible to obtain the similar structure as mentioned above by makinguse of a selective CVD method such as the W-CVD method which makes itpossible to selectively deposit a material only on a conductivematerial.

It is also possible, at the occasion of forming a contact hole 4 bymeans of the RIE method so as to connect with the first wiring layer 1covered. on its upper surface with a barrier film 11, to selectivelyremove a portion of the barrier film 11 disposed on the upper surface ofthe first wiring layer 1 as shown in FIG. 9A, or to stop the etching bythe RIE method immediately after the upper surface of the barrier film11 is exposed as shown in FIG. 9B.

The barrier film may be substituted by a CMP-stopper layer or by a filmfunctioning as a barrier film as well as a CMP-stopper layer. TheCMP-stopper layer may be formed of either a conductive film or aninsulating film as long as it is low in abrasion rate as compared withthe abrasion rate of the Al film 8 in the CMP polishing. However, if aninsulating film is to be employed, it can not be disposed on the bottomof the contact hole 4.

EXAMPLE 2

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 10A to 10F.

First of all, a first wiring layer 1 is formed on an Si substrate (notshown) provided with an element. This first wiring layer 1 is partiallyseparated from each other via an insulating film 2. Then, a firstinterlayer insulating film 3 is formed all over the surface of the Sisubstrate.

Then, the first interlayer insulating film 3 is selectively etched bymaking use of photolithography and RIE to a depth reaching to the firstwiring layer 1, thus forming a contact hole. Namely, the contact hole.connected with the first wiring layer 1 is formed.

Then, an Si film 7 is deposited all over the substrate by means ofLP-CVD method, and abraded by means of the CMP method in such an extentthat the Si film 7 is left remained in the interior of the contact hole(FIG. 10A).

Then, a second interlayer insulating film 12 is formed all over theupper surface (FIG. 10B) and then worked by making use ofphotolithography process and RIE process to form a wiring groove (FIG.10C). In the step of FIG. 10B, the thickness of the second inter-layerinsulating film 12 should be made almost the same as that of a secondwiring layer to be formed in the subsequent step.

Then, the native oxide film and impurities on the surface of the Si film7 are removed by means of Ar ion sputtering in a vacuum, and then an Alfilm 8 and a Ti film 9 are successively formed on the entire surface ofthe Si film 7 in a vacuum in order to prevent the surface of the Si film7 from being reoxidized or contaminated (FIG. 10D).

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilm 8 and at the same time allowing a silicide-forming reaction to takeplace between the Si film 7 and the Ti film 9. Through the formation ofthe silicide, the Si film 7 is absorbed by the Ti film 9. As a result ofthis step, a Ti/Ti silicide film 10 is formed (FIG. 10E).

Finally, the Ti/Ti silicide film 10 and a superfluous portion of the Alfilm 8 are removed by means of the CMP method. As a result, an Al plugand an Al wiring layer (a second wiring layer) both consisting of the Alfilm 8 are formed in the interiors of the contact hole 4 and the wiringgroove 5, respectively (FIG. 10F).

Since the quantity of Si to be substituted by the Al film 8 is limitedas in the case of the Example 1, the quantity of Si to besolid-solubilized in the Al film 8 can be minimized, thus making itpossible to lower the electric resistivity of the wiring layer.

According to this example, the second interlayer insulating film 12 isformed directly on the surface of the first interlayer insulating film3. However, it is also possible to form an RIE-stopper layer.

For example, if an insulating film exhibiting a high selectivity inrelative to the second interlayer insulating film 12 in the RIE processis formed on the surface of the first interlayer insulating film 3 andthen employed as an RIE-stopper layer at the occasion of forming awiring groove, it is possible to inhibit the trenching (a phenomenonthat the bottom of wiring groove is caused to curve) that can be seen atthe occasion of forming the wiring groove.

It is also possible to form a TiN film as a barrier film in subsequentto the formation of the contact hole and then to form the Si film 7.When a barrier film is formed in this manner, it is possible to inhibitthe reaction between the first wiring layer 1 and the Al film 7 at thebottom of the contact hole.

EXAMPLE 3

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 11A to 11E.

First of all, a first wiring layer 1 is formed on an Si substrate (notshown) provided with an element. This first wiring layer 1 is partiallyseparated from each other via an insulating film 2. Then, an interlayerinsulating film 3 consisting of SiO₂ is formed all over the surface ofthe Si substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole. Namely, the contact hole connectedwith the first wiring layer 1 is formed.

Then, an Si film 7 is deposited all over the substrate by means ofLP-CVD method in a manner to avoid the generation of voids in theinterior of the contact hole, and abraded by means of the CMP method insuch an extent that the Si film 7 is left remained in the interior ofthe contact hole (FIG. 11A).

Then, a wiring groove 5 is formed in the interlayer insulating film 3(FIG. 11B). This wiring groove 5 is formed so as to include the regionof the contact hole.

Then, the native oxide film and impurities on the surface of the Si film7 are removed by means of Ar ion sputtering (reverse sputtering) in avacuum, and then an Al film 8 and a Ti film 9 are successively formed onthe entire surface of the Si film 7 in a vacuum in order to prevent thesurface of the Si film 7 from being reoxidized or contaminated (FIG.11C).

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilm 8 and at the same time allowing a silicide-forming reaction to takeplace between the Si film 7 and the Ti film 9. Through the formation ofthe silicide, the Si film 7 is absorbed by the Ti film 9. As a result ofthis step, a Ti/Ti silicide film 10 is formed (FIG. 11D).

Finally, the Ti/Ti silicide film 10 and a superfluous portion of the Alfilm 8 are removed by means of the CMP method. As a result, an Al plugand an Al wiring layer (a second wiring layer) both consisting of the Alfilm 8 are formed in the interiors of the contact hole and the wiringgroove 5, respectively (FIG. 11E).

According to this example, SiO₂ is employed as a material for theinterlayer insulating film 3. The etching rate of SiO₂ by means of RIEmethod can be made faster than that of Si by suitably adjusting theetching conditions. Therefore, when the wiring groove 5 is formed in theinterlayer insulating film 3 by means of RIE method, the Si film 7 iscaused to protrude from the surface of the wiring groove 5 as shown inFIG. 11B.

As a result, the contacting surface between the Si film 7 and the Alfilm 8 can be increased whereby increasing the diffusing route of Siinto the Al film 8. As a result, the substitution of Al film 8 for theSi film 7 can be easily proceeded.

EXAMPLE 4

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 12A to 12E.

First of all, a first wiring layer 1 is formed on an Si substrate (notshown) provided with an element. Then, a contact hole 4 and a wiringgroove 5 are successively formed in an interlayer insulating film 3(FIG. 12A).

Then, a native oxide film formed on the upper surface of the firstwiring layer 1 which has been exposed on the bottom of the contact hole4 is removed.

Then, an Si film 7 is deposited all over the substrate by means of CVDmethod and then abraded by means of the CMP method in such a way thatthe Si film 7 is selectively left remained in the interiors of thecontact hole 4 and the wiring groove 5 (FIG. 12B).

Then, the native oxide film and impurities on the surface of the Si film7 are removed, and then depositions of an Al film 8 by means of a biassputtering method and of a Ti film 9 by means of the ordinary sputteringmethod are successively performed on the entire surface of the Si film 7in a vacuum (FIG. 12C).

This bias sputtering method is performed as follows. Namely, a sputtertarget is placed on the cathode side, and a substrate is disposed on theanode side. Then, a high frequency power is applied to the anode therebyto generate plasma, and the formation of film is performed while pullingthe Ar ions toward the substrate by means of the self-bias impressed tothe substrate.

It is possible with this bias sputtering method to form a filmexhibiting a high step coverage due to the physical etching effect of Arions being pulled toward the substrate. However, the film thus formedcontains a large amount of Ar gas thereby entrapping a large number ofvoids in the film, thus making the film porous.

However, in this example, the Al film 8 is formed by means of the biassputtering method under the conditions positively enabling the voids to.be formed.

Thereafter, the substrate is heat-treated for 30 minutes at atemperature of 400° C., whereby allowing the Si film 7 to be substitutedby the Al film 8 and at the same time allowing a silicide-formingreaction to take place between the Si film 7 and the Ti film 9. Throughthe formation of the silicide, the Si film 7 is absorbed by the Ti film9. As a result of this step, a Ti/Ti silicide film 10 is formed (FIG.12D).

Finally, the Ti/Ti silicide film 10 and a superfluous portion of the Alfilm 8 are removed by means of the CMP method. As a result, an Al plugand an Al wiring layer (a second wiring layer) both consisting of the Alfilm 8 are formed in the interiors of the contact hole and the wiringgroove 5, respectively (FIG. 12E).

According to this example, a porous Al film 8 which has been formed bymeans of bias sputtering is employed as a conductive film. This porousAl film 8 is low in crystallinity and very small in crystal graindiameter though it is a polycrystalline film.

Accordingly, the total area of the crystal boundary crossing through theporous Al film 8 is larger as compared with that of densepolycrystalline Al film, and hence the porous Al film 8 is provided witha large grain boundary area, thus facilitating the diffusion of atoms.As a result, the self-diffusion. rate of Al atoms in this porous Al film8 is relatively high.

The Al wiring formed with an Al film exhibiting a high self-diffusionrate is generally poor in electro-migration resistance and instress-migration resistance, so that it cannot be employed as a wiring.

However, in the case of this invention, the porous Al film which isformed at first is not directly employed as a wiring. Namely, what isemployed as a wiring layer in this invention is the Al film 8 whichsubstitutes for the Si film 7 filled in the interiors of the contacthole 4 and the wiring groove 5. Therefore, the wiring is not porous,thus raising no problem.

Because, since the substitution reaction. is not dependent on the macroAl film quality but on the mutual diffusion between Al atoms and Siatoms. Namely, through the substitution between the Si film 7 and the Alfilm 8, the Al film is changed into a sufficiently dense Al film whichis useful as a wiring layer.

Furthermore, the porous Al film is not only high in self-diffusion rateof Al atoms, but also, effective in promoting the diffusion of Si atomsof the Si film 7 (a film to be substituted) into the Al film 8. When thediffusion of Si in the Al film 8 is promoted, Si atoms can be easilytrapped in the Ti film within a short period of time, thus making itpossible to shorten the time required for the substitution/absorptionstep and to lower the temperature of the substitution/absorption step.

These effects can be obtained not only through the use of the porous Alfilm but also through the use of an amorphous Al film, since theamorphous Al film is effective in accelerating the diffusion rate.Further, not only the transformation of Al film 8 into a porous oramorphous Al film but also the transformation of Si film 7 into a porousor amorphous Si film is effective in accelerating the diffusion rate ofAl (a material constituting a conductive film) into the Si film 7 (afilm to be substituted), thus making it possible to shorten the timerequired for the substitution/absorption step and to lower thetemperature of the substitution/absorption step.

EXAMPLE 5

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 13A to 13F.

First of all, a first wiring layer 1 is formed on an Si substrate (notshown) provided with an element. Then, an interlayer insulating film 3is formed all over the surface of the Si substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole 4, and at the same time a wiringgroove 5 is selectively formed likewise at a region including thiscontact hole 4. Namely, the contact hole 4 connected with the firstwiring layer 1 and the wiring groove 5 are successively formed (FIG.13A).

Then, an Si film 7 is deposited all over the substrate by means ofLP-CVD method in a manner to avoid the Si film 7 from becoming toothick. Namely, the interiors of the contact hole 4 and the wiring groove5 are not completely filled with the Si film 7 (FIG. 13B). The Si film 7is employed in this example not only as a film for the substitution butalso as a liner exhibiting an excellent wettability to Al.

Then, an Al film 8 having a thickness of about ⅓ of the entire filmthickness (the final film thickness) is deposited all over the surfaceof the substrate without heating by making use of a directionalsputtering method, and then an Al film 8 having a thickness of about ⅔of the entire film thickness is deposited all over the surface of thesubstrate, while heating the substrate, in a vacuum by making use of theordinary sputtering method (FIG. 13C).

As for the directional sputtering method, a collimation sputteringmethod or a low pressure-long distance sputtering method for instancecan be employed. When the sputtering of the Al film 8 is performed whileheating the substrate, the fluidity of the Al film 8 can be increased,thus making it possible to easily fill the interiors of the contact hole4 and wiring groove with the Al film 8.

Furthermore, when the sputtering of the Al film 8 is performed whileheating the substrate, the surface diffusion of the Al film 8 can beaccelerated due to the kinetic energy of the incoming sputteredparticles (Al particles), so that the interiors of the contact hole 4and wiring groove can be with the Al film 8 within a short period oftime.

Then, a Ti film 9 is formed on the entire surface of the resultantsubstrate by making use of a sputtering method (FIG. 13D).

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilm 8 and at the same time allowing a silicide-forming reaction to takeplace between the Si film 7 and the Ti film 9. Through the formation ofthe silicide, the Si film 7 is absorbed by the Ti film 9. As a result ofthis step, a Ti/Ti silicide film 10 is formed (FIG. 13E).

Finally, the Ti/Ti silicide film 10 and a superfluous portion of the Alfilm 8 are removed by means of the CMP method. At this occasion, the TiNfilm 6 formed as a barrier film on the upper portion of the substrate isalso removed by means of the CMP method (FIG. 13F). As a result, an Alplug and an Al wiring layer (a second wiring layer) both consisting ofthe Al film 8 are formed in the interiors of the contact hole and thewiring groove 5, respectively.

EXAMPLE 6

First of all, a first wiring layer is formed on an Si substrate providedwith an element. Then, an interlayer insulating film is formed all overthe surface of the Si substrate.

Then, the interlayer insulating film is selectively etched by making useof photolithography and RIE to a depth reaching to the first wiringlayer, thus forming a contact hole, and at the same time a wiring grooveis selectively formed likewise at a region including this contact hole.Namely, the contact hole connected with the first wiring layer and thewiring groove are successively formed.

Then, a thin Si film is deposited on the inner walls of the contact holeand wiring groove by means of LP-CVD method.

For example, the thickness of the Si film may be 5 to 50 nm when thediameter of the opening of contact hole is 0.3μ and the depth thereof is0.9μ. This thin Si film can be employed a liner having an excellentwettability to the Al film.

Then, an Al film having a thickness of 0.8μ is deposited all over thesurface of the substrate without heating by making use of a directionalsputtering method, after which the substrate is heated at a temperatureof 400 to 500° C. in a vacuum. As a result, the Al film is fluidized bythe heating, thus filling the interiors of the contact hole and thewiring groove with Al.

Although the Al film is formed herein by means of a directionalsputtering method, the film thickness of Al film located at the bottomof the contact hole is relatively small in thickness. This thin Al filmis more likely to be agglomerated and separated. When the Al film isseparated in this manner, the route for the surface diffusion of the Alfilm is lost so that the Al film would not be fluidized.

However, since the Si film exhibiting an excellent wettability to the Alfilm is disposed an underlying layer in this example, the agglomerationand separation of the Al film can hardly take place, thus making itpossible to fill the interiors of the contact hole and the wiring groovewith the Al film. Further, since these Al and Si are allowed to undergoa mutual diffusion, the Si in the Si film gradually diffuses into the Alfilm in simultaneous with the fluidization of the Al film.

Then, a Ti film is formed on the entire surface of the resultantsubstrate by making use of a sputtering method while maintaining thetemperature of the substrate to the fluidization temperature of the Alfilm. As a result, the Si film is substituted by the Al film, and at thesame time a silicide-forming reaction is allowed to take place betweenthe Si film diffused into the Al film and the Ti film at the uppersurface of the Al film, thus forming a stable Ti/Ti silicide film.

Finally, the Ti/Ti silicide film and a superfluous portion of the Alfilm are removed by means of the CMP method. As a result, an Al plug andan Al wiring layer (a second wiring layer) both consisting of the Alfilm are formed in the interiors of the contact hole and the wiringgroove, respectively.

EXAMPLE 7

First of all, a first wiring layer is formed on an Si substrate providedwith an element. Then, an interlayer insulating film is formed all overthe surface of the Si substrate.

Then, the interlayer insulating film is selectively etched by making useof photolithography and RIE to a depth reaching to the first wiringlayer, thus forming a contact hole, and at the same time a wiring grooveis selectively formed likewise at a region including this contact hole.Namely, the contact hole connected with the first wiring layer and thewiring groove are successively formed.

Then, a TiN film as a barrier film is formed all over the upper surfaceof the substrate by means of a sputtering method.

Then, a thin Si film is deposited on the inner walls of the contact holeand wiring groove by means of LP-CVD method. This Si film can beutilized as a film for increasing the nucleus for Al in addition to theutilization as the aforementioned substitutive film.

Then, an Al film is deposited all over the surface of the substrate bymeans of a CVD method wherein dimethyl aluminum hydride is employed as araw material and temperature of the substrate is set to a temperature of300 to 400° C.

In this case, since the Si film is disposed as an underlying layer forthe Al film, i.e. since there are a large number of nuclei for Al, theAl film can be allowed to grow uniformly. As a result, the interiors ofthe contact hole and the wiring groove can be filled with the Al film.

Then, the temperature of the substrate is increased up to 450° C. and atthe same time, a Ti film is deposited on the surface of the substrate ina vacuum by means of a sputtering method. During these processes ofincreasing the substrate temperature and the Ti-sputtering, the Si filmis substituted by the Al film, and at the same time a silicide-formingreaction is allowed to take place between the Si film and the Ti film,thus forming a Ti silicide film, thus allowing the Si film to beabsorbed by the Ti film.

If the substitution between the Al film and the Si film is insufficientin this case, the heating should preferably be continued even after theformation of the Ti film.

Finally, the Ti film, the Ti silicide film and a superfluous portion ofthe Al film are removed by means of the CMP method. As a result, an Alplug and an Al wiring layer (a second wiring layer) both consisting ofthe Al film are formed in the interiors of the contact hole and thewiring groove, respectively.

EXAMPLE 8

This example is applicable to all of the previous Examples 1 to 7.

There is a possibility in the method of filling the interiors of thecontact hole and the wiring groove with an Si film that a CMP abrasiveis left attached to the surface of the Si film after the step ofremoving a superfluous Si film disposed outside the contact hole orwiring groove by means of the CMP method, which is performed insubsequent to the step of forming the Si film.

Further, there is a possibility that a halide is left attached to thesurface of the Si film after the step of removing a superfluous Si filmdisposed outside the contact hole or wiring groove by means of the CDEetch-back method or by means of the RIE etch-back method.

Furthermore, when the substrate is exposed to the external atmosphereafter finishing the step of filling the interiors of the contact holeand wiring groove with an Si film, the surface of the Si film may becovered by a native oxide film or contaminated with an adhesion ofimpurities such as carbon in the air atmosphere.

The presence of these native oxide film and impurities not onlyobstructs the substitution reaction between Al and Si, i.e. a mutualdiffusion therebetween, but also gives rise to various problems such asan increase in electric resistance due to these residues or an increasein time required for the aforementioned substitution reaction.

Accordingly, the employment of a wet etching using a dilute HF orammonium fluoride is effective in removing these native oxide film andimpurities. Further, if the surface of the Si film is subjected to ahydrogen termination treatment by making use of a super pure watercontaining not more than 10 ppb of oxygen, the natural oxidation due tothe exposure to the air atmosphere can be effectively inhibited.

The employment of a dry etching using an Ar ion sputtering is effectivein removing these native oxide film and impurities. Furthermore, if theAl film is formed in a vacuum without breaking vacuum after the dryetching, the re-oxidation of the surface of the Si film can beeffectively inhibited.

When a method of filling the interiors of the contact hole and thewiring groove with an Si film is performed by a process wherein the Sifilm is entirely deposited at first and then the Si film is selectivelyremoved by means of a dry etching process such as the CDE etch-backmethod or the RIE etch-back method so as to leave the Si film only inthe interiors of the contact hole and the wiring groove, there-oxidation of the surface of the Si film can be effectively inhibited,if the Al film is formed in a vacuum without breaking vacuum after thedry etching.

Further, since the native oxide film to be formed on the surface of theSi film that has been filled in the interiors of the contact hole andwiring groove is extremely thin, the native oxide film can be reduced bymaking use of Al. Thus, if a thermal sputtering wherein the sputteringis performed while heating the substrate is employed, the native oxidefilm can be reduced during the formation of the Al film, thus assuringthe route for the mutual diffusion.

EXAMPLE 9

This example is applicable not only to all of the previous Examples 1 to7, but also to the cases wherein Example 8 is applied to Examples 1 to7.

There is a possibility that the surface of the first wiring layercontacting with the contact hole may be covered by a native oxide filmor impurities, thus giving rise to an increase in contact resistancebetween the upper wiring layer and the lower wiring layer due to thepresence of these native oxide film and impurities.

The removal of these native oxide film and impurities can be effectivelyperformed before the step of forming the Si film and in a vacuum by theemployment of an Ar ion sputtering or a chemical etching using anetching gas containing a halogen. Furthermore, the re-oxidation of thesurface of the wiring layer can be effectively inhibited if the Si filmis formed in a vacuum without breaking vacuum after the etching.

Since the employment of a single-wafer processing type apparatus isessential for carrying out a physical etching such as the Ar ionsputtering, the formation of Si film in subsequent to the removal of thenative oxide film should preferably be performed by making use of asingle-wafer processing type apparatus.

By contrast, in the case of chemical etching using an etching gas, itcan be performed by making use of either a single-wafer processing typeapparatus or a batch type apparatus. Further, the formation of Si filmin subsequent to the removal of the native oxide film can be performedby making use of either a single-wafer processing type apparatus or abatch type apparatus.

Alternatively, the native oxide film on the surface of the Al wiringlayer may be reduced by depositing a film consisting of a reductivematerial such as Ti on the surface of the first wiring layer. Ti is ahighly reductive material so that the oxide film (Al₂O₃ film) on thesurface of the Al wiring layer can be reduced by the Ti film, and at thesame time, the presence of Ti film is effective in lowering the contactresistance.

However, since Ti is reactive to Si, thus generating a silicifyingreaction, there is a possibility of producing a Ti silicide film througha reaction between the Ti film and the Si film before the substitutionreaction between the Si film and the Al film takes place in the presentinvention which is featured in the utilization of the substitutionreaction between the Si film and the Al film. If this Ti silicide filmis produced, it will give a bad influence to the performance of thedevice of the present invention. This problem can be overcome by forminga TiN film as a barrier film on the surface of the Ti film in a vacuumwithout breaking vacuum or immediately after the previous step. It ispossible with the formation of the TiN film to inhibit the silicifyingreaction and at the same time to lower the contact resistance.

EXAMPLE 10

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 14A to 14D.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate (not shown) provided with an element. Then, an interlayerinsulating film 3 is formed all over the upper surface of the substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole, and at the same time a wiringgroove is selectively formed likewise at a region including this contacthole. Namely, the contact hole connected with the first wiring layer 1and the wiring groove are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer 1 which has been exposed on the bottom of the contact hole4 is removed by means of a surface treatment. Then, an Si film 7 isdeposited all over the substrate by means of CVD method in a mannerwhich makes it possible to prevent any void from generating in theinteriors of the contact hole and the wiring groove, thus obtaining theSi film 7 exhibiting an excellent step coverage.

Then, the Si film 7 is selectively removed by means of the CMP method orCDE method so as to leave the Si film 7 only in the interiors of thecontact hole and the wiring groove 5, thus removing any superfluousportion of the Si film 7 (FIG. 14A).

Then, the native oxide film on the surface of the Si film 7 are removedby way of a wet surface treatment or a dry surface treatment, e.g. areverse sputtering for instance, and thereafter, an Al film 8 isdeposited all over the upper surface of the resultant substrate.

In this case, if the Si film 7 is removed to such an extent that aportion of the Si film 7 which has been filled in the interior of thewiring groove is removed by the CDE method in the step of FIG. 14A, thedeposition of the Al film 8 should be performed in such a manner thatthe wiring groove can be completely filled with the Al film 8. Because,if the interior of the wiring groove is not filled fully with the. Alfilm 8, a Ti film may be formed even in the interior of the wiringgroove in a subsequent step, thus possibly making it difficult to removethe Ti film or Ti silicide film after the step of substitution betweenthe Si film and the Al film.

Then, the substrate is transferred to a separate chamber withoutbreaking vacuum, and disposed to face a Ti target with a shadow maskinterposed therebetween. Under this condition, Ti film 9 a is formed viathe shadow mask on the surface of the Al film 8. Since the deposition ofthe Ti film 9 a is performed via the shadow mask, a plurality of the Tifilms 9 a arrayed in a predetermined pitch can be obtained.

Then, after another Al film 8 is deposited all over the upper surface ofthe resultant substrate, another Ti film 9 a is formed via the shadowmask on the surface of the Al film 8 in a vacuum without breakingvacuum. In this case, the position of the shadow mask is offset from theprevious location of the shadow mask. As a result, a group of Ti films 9a which are offset in parallel from the previous group of Ti films 9 acan be obtained. It is possible in this manner to minimize theoverlapped portion (in the vertical direction) between these groups ofTi films 9 a. Thereafter, another Al film 8 is deposited again all overthe upper surface of the resultant substrate (FIG. 14B).

If the deposition steps of the Al film 8 and the Ti film 9 a arealternately repeated, the contacting surface between the Al film 8 andthe Ti film 9 a can be effectively increased. Further, since theoverlapped portion (in the vertical direction) between these groups ofTi films 9 a can be minimized as mentioned above, it is possible toeffectively trap the Si atoms which have been diffused into the Al film8 in the subsequent heat treatment step by the Ti films 9 a.

Moreover, when the deposition steps of the Al film 8 and the Ti film 9 aare repeated in a vacuum without breaking vacuum, it is possible toprevent any native oxide film from being formed at the interface betweenthe Al film 8 and the Ti film 9 a.

In the mutual diffusion between the Si film 7 and the Al film 8, as wellas in the silicifying reaction between the Si film 7 and the Ti film 9a, if a native oxide film is formed at the interface of these films, themutual diffusion would be suppressed by the native oxide film and thesilicifying reaction would be also obstructed by the native oxide film,thus suppressing the silicifying reaction.

Therefore, additional step for removing the native oxide film isrequired for avoiding these suppressions. However, if a plurality of Tifilms 9 a, each functioning as an absorption film, are successivelydeposit in vacuum as mentioned above, the step for removing the nativeoxide film is no more required to be performed.

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilm 8 and at the same time allowing a silicide-forming reaction to takeplace between the Si film 7 and the Ti film 9. Through the formation ofthe silicide, the Si film 7 is absorbed by the Ti film 9. As a result ofthis step, a Ti/Ti silicide film 10 is formed (FIG. 14C).

Since the effective contacting surface between the Al film 8 and the Tifilm 9 a is large and since the overlapped portion (in the verticaldirection) between the Ti films 9 a is small in the case of thisexample, the substitution/absorption in the step of FIG. 14C can beeffectively enhanced.

Namely, the Si atoms in the Si film 7 that have been diffused into theAl film 8 are trapped (silicided) at the interface between the Al film 8and the Ti film 9 a. Since the effective contacting surface between theAl film 8 and the Ti film 9 a is large in the case of this example, theprobability of the aforementioned trapping would be increased, thusmaking it possible to shorten the time required for thesubstitution/absorption process.

In the foregoing explanation on this example, only two layers of Ti film9 a are employed. However, it is also possible to employ an increasednumber of Ti layer, whereby further saving the time required for thesubstitution/absorption process.

Finally, the Ti film, the Ti silicide film 10 and a superfluous portionof the Al film 8 are removed by means of the CMP method. As a result, anAl plug and an Al wiring layer (a second wiring layer) both consistingof the Al film 8 are formed in the interiors of the contact hole and thewiring groove, respectively.

In the foregoing explanation on this example, a plurality of Ti films 9a are formed in the same layer by making use of a shadow mask. However,it is also possible to employ a patterning process through a combinationof the photolithography and RIE or a combination of the photolithographyand wet etching.

In this case, a more fine Ti film can be formed as compared with the Tifilm 9 a to be formed by making use of a shadow mask, thus making itpossible to further increase the contact area between the Ti film andthe Al film 8 and hence to enable more efficient absorption of Si film.

Furthermore, according to these methods, it is also possible to arrangethe layout of plural Ti films in the same layer in conformity with thequantity of the underlying Si layer, thus avoiding the formation ofsuperfluous Ti film for the absorption of the Si film.

A specific example of this method will be explained below.

First of all, a first wiring layer is formed on an Si substrate providedwith an element. Then, an interlayer insulating film is formed all overthe upper surface of the substrate.

Then, the interlayer insulating film is selectively etched by making useof photolithography and RIE to a depth reaching to the first wiringlayer, thus forming a contact hole, and at the same time a wiring grooveis selectively formed likewise at a region including this contact hole.Namely, the contact hole connected with the first wiring layer an thewiring groove are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer which has been exposed on the bottom of the contact hole isremoved by means of a surface treatment. Then, an Si film is depositedall over the substrate by means of CVD method in a manner which makes itpossible to prevent any void from generating in the interiors of thecontact hole and the wiring groove, thus obtaining the Si filmexhibiting an excellent step coverage.

Then, the Si film is selectively removed by means of the CMP method orCDE method so as to leave the Si film only in the interiors of thecontact hole and the wiring groove, thus removing any superfluousportion of the Si film.

Then, an Al film is deposited all over the upper surface of theresultant substrate.

In this case, if the Si film is removed to such an extent that a portionof the Si film which has been filled in the interior of the wiringgroove is removed by the CDE method or RIE method in the previous step,the deposition of the Al film should be performed in such a manner thatthe wiring groove can be completely. filled with the Al film. Because,if the interior of the wiring groove is not filled fully with the Alfilm, a Ti film may be formed even in the interior of the wiring groovein a subsequent step, thus possibly making it difficult to remove the Tifilm or Ti silicide film (to be formed in the subsequent step) in thesubsequent step.

Then, Ti film is formed on the Al film in a vacuum without breakingvacuum.

Then, at least a portion of the Ti film which has been deposited on thecontact hole and wiring groove is partitioned by making use ofphotolithography and RIE.

In this case, the Ti film may be etched under the condition of etchingratio wherein the Al film disposed below the Ti film can be sufficientlyleft remained, or alternatively both Ti film and Al film areconcurrently etched under the condition of etching ratio wherein the Sifilm filled in the interior of the wiring groove can be sufficientlyleft remained. Thereafter, the native oxide films formed on the surfacesof the exposed Si film, Ti film and Al film are removed, and then theinterior of the wiring groove is again filled completely with an Alfilm.

The reason for re-filling the wiring groove with an Al film is asfollows. Namely, since there is a possibility of Ti film being depositedon the inner wall of the wiring groove depending on the filling ratio ofthe Si film as mentioned above, if the interior of the wiring groove isnot filled fully with the Al film, it may become difficult to remove theTi film or Ti silicide film in the subsequent step.

Then, the native oxide films on the surfaces of the Ti film and Al filmor the native oxide film on the surface of the Si film (when it isexposed) are removed after the aforementioned partitioning step of Tifilm. Thereafter, an Al film is again deposited all over the uppersurface of the resultant substrate by means of anisotropic sputteringmethod such as a long slow sputtering or collimation sputtering so as toavoid the formation of voids in the recessed portion formed by thepartitioning of the Ti film.

Since a native oxide film would be formed on the surface of each film atthe partitioning step of Ti film, there is a high possibility that thesilicifying reaction between the Si to be diffused into the Al film inthe subsequent step (the substitution/absorption step accompanying aheat treatment) and the Ti film would be obstructed, and at the sametime the diffusion between Si and Al would be hindered.

Therefore, it is required to remove the native oxide films on thesurfaces of the Ti film, Al film and Si film after the partitioning stepof Ti film, thus promoting the substitution reactions, i.e. thediffusion between Al and Si, and the silicifying reaction between Si andTi.

The reason for depositing an Al film after the partitioning step of Tifilm in a manner to avoid the formation of voids at the interfacebetween the Ti film and the Al film is to assure a route which enablesthe Si to diffuse and reach to the Ti film at the occasion of thesubstitution/absorption step, thereby to ensure the silicifyingreaction.

When the Al film and the partitioned Ti film are formed in this manner,the contact area between the Ti film and the Al film can be effectivelyincreased, thus making it possible to effectively carry out thesubstitution/absorption reaction.

Since the Si atoms that have been diffused into the Al film 8 aretrapped (silicided) at the interface between the Al film and the Tifilm, an increase in interface between the Al film and the Ti film leadsto an increase in probability of trap, thus making it possible toshorten the time required for the substitution/absorption process.

If the partitioning step of the Ti film and the deposition step of theAl film are repeated plural times, the substitution/absorption can beperformed more efficiently.

If the patterning of the Ti film is performed, in the process ofrepeating the partitioning step of the Ti film and the deposition stepof the Al film, in such a manner that the lower partitioned Ti filmregion does not overlap with the upper partitioned Ti film region inrelative to the Si film filled in the contact hole or wiring groove, theSi disposed below the Ti film can be more effectively trapped.

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C. whereby allowing the Si film to be substituted by the Al filmand at the same time allowing a silicide-forming reaction to take placebetween the Si film and the Ti film. Through the formation of thesilicide, the Si film is absorbed by the Ti film.

Finally, the Ti film which is not employed for the silicifying reaction,the Ti silicide film and a superfluous portion of the Al film are allremoved by means of the CMP method. As a result, an Al plug and an Alwiring layer (a second wiring layer) both consisting of the Al film areformed in the interiors of the contact hole and the wiring groove,respectively.

In the foregoing explanation of this example, the Ti film is partitionedby making use of a shadow mask and then laminated together with the Alfilm. However, it is also possible to shorten the substitution time bysimply laminating a plurality of contiguous. Ti films (not partitioned)with the Al films as compared with the structure where only one Ti filmis formed on the Al film.

Furthermore, if the Ti film is made thinner, the Ti film is turned intoa mesh structure when it is viewed microscopically, so that the Si atomsdiffusing through the Al film may pass through the Ti film or asilicided thin Ti film, thus reaching an upper Ti film and reacting(silicifying reaction) with this upper Ti film. This phenomenon can befurther promoted when a many number of thin Ti films are laminated witha many number of the Al films.

The gist of the present invention resides in the increase of the contactarea between a conductive film and an absorption film. The increase ofthis contact area can be achieved by forming recessed portions orprojected portions on the surface of the conductive film. Specificexamples of this structure will be explained below.

For example, when an Al film is formed by means of sputtering whileheating a substrate, an agglomeration of Al occurs at the initial stageof sputtering, thus forming an Al cluster. When this Al cluster isformed, the Al particles sputtered subsequently diffuse over thesubstrate and absorbed by the Al cluster, thus growing the Al clusterand hence forming an Al film having an extremely roughened surface.

When a Ti film is formed on this Al film having an extremely roughenedsurface, the contact area between the Al film and the Ti film can beincreased, whereby increasing the possibility to trap the Si atoms ofthe lower Si film by the interface between the Al film and the Ti film.

It is also possible to introduce Ti atoms into the Al film formed inadvance by means of ion implantation method, thereby dispersing Ti atomson the surface region of the Al film. According to the ion implantationmethod, it is possible to entrap Ti atom in the Al film without invitinga reaction between Al and Ti, and at the same time to destroy thecrystallinity of the Al film thereby to form an amorphous Al filmexhibiting a high self-diffusion coefficient. As a result, it ispossible to shorten the substituting time in the subsequent substitutionstep.

EXAMPLE 11

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 15A to 15H.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate (not shown) provided with an element. This first wiring layer1 is partially separated from each other via an insulating film 2. Then,an interlayer insulating film 3 is formed all over the surface of the Sisubstrate (FIG. 15A).

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole 4, and at the same time a wiringgroove 5 is selectively formed likewise at a region including thiscontact hole 4 (FIG. 14B). Namely, the contact hole 4 connected with thefirst wiring layer 1 and the wiring groove 5 are successively formed.

Then, a boron doped amorphous Si film 7 is deposited all over thesubstrate by means of LP-CVD method in a manner which makes it possibleto prevent any void from generating in the interior of the contact hole.Then, the Si film 7 is selectively etched away by means of the CDEmethod so as to leave the Si film 7 only in the interior of the contacthole 4 (FIG. 15C).

Then, the native oxide film and impurities on the surface of the Si film7 are removed by means of Ar ion sputtering in a vacuum, and then an Alfilm 8 is formed on the entire surface of the Si film 7 in a vacuumwithout breaking vacuum (FIG. 15D).

Thereafter, the substrate is heat-treated in an electric furnace for onehour at a temperature of 450° C., whereby allowing Si to be diffused inthe Al film 8. As a result of this heat treatment, the surface of the Alfilm is roughened and Si is diffused in the Al film, part of thediffused Al being uniformly turned into nodules (FIG. 15E).

Then, the native oxide film formed on the surface of the Si film 7 andon the surface of the precipitated Si is removed by means of Ar ionsputtering in a vacuum, and then a Ti film 9 is formed by means ofsputtering on the entire surface of the resultant substrate in a vacuumwithout breaking vacuum (FIG. 15F).

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C., whereby allowing Si in the Al film to react with the Ti filmto form a TiSi compound, thereby allowing Si to be absorbed by the Tifilm. During this step, an AlTi compound is also formed as an upperlayer 10 in addition to the TiSi compound (FIG. 15G).

Finally, the Ti film, the TiSi compound layer, the AlTi compound layerand a superfluous portion of the Al film are all removed by means of theCMP method. As a result, an Al plug 8 a and an Al wiring layer (a secondwiring layer) 8 b both consisting of the Al are formed in the interiorsof the contact hole and the wiring groove, respectively.

As explained in Example 10, the surface of an Al film can be roughenedby making use of a thermal sputtering, and, owing to this roughenedsurface of Al film, the contact area between the Al film and the Ti filmcan be increased, thus increasing the probability of trapping Si. Thisroughening of an Al film can be also effected by heat-treating the Alfilm formed in advance as in the case of this example, thus obtainingalmost the same effect.

If this heat treatment is long enough to allow Si to diffuse and mix inan Al film as in the case of this example, Si can be uniformly dispersedthroughout the Al film. However, depending on the layout of the wiringpattern for an LSI, a region containing a large quantity of Si and aregion containing a small quantity of Si may be non-uniformly formed.Therefore, if the quantity of Si is relatively large in an underlyinglayer, the upper Ti layer is required to absorb a large quantity of Si.Since the heat treatment time is determined by the time required forfinishing the substitution of Si of a region on a substrate where amaximum quantity of Si is contained, the heat treatment time isprolonged by the existence of an Si-enriched region. Accordingly, if thedistribution of Si in the Al film is made uniform in advance as in thecase of this example, the substitution time would be shortened, andhence the total processing time would be shortened as a whole.

When a heat treatment is performed to allow Si to be absorbed in anupper Ti film, void may be formed in the interior of the first Al wiringlayer or in the interior of the second Al wiring layer. The generationof voids is assumed to be caused by a stress gradient to be formedbetween the surface region of the Al film which has been increased involume due to the absorption of Si and the wiring groove or contact holeportion which has been decreased in volume due to the diffusion of Si.

In the case of this example however, it is characterized in that a heattreatment is performed for allowing the diffusion and mixing (a partialsubstitution) of Al and Si before the heat treatment for the absorptionof Si into a Ti film. If this method is adopted, Si can be uniformlydistributed throughout the Al film by the aforementioned preliminaryheat treatment. As a result, the stress gradient due to the gradient ofSi concentration in the heat treatment for the absorption of Si into aTi film can be alleviated.

In the foregoing explanation of this example, the substrate isheat-treated in an electric furnace before a Ti film is formed. However,if the quantity of Si is relatively small, the heat treatment for theaforementioned diffusion and mixing can be shortened, or alternatively,a method of depositing Al while heating the substrate as explained inExample 10 may be employed. When a cluster tool is employed in this casefor the formation of Ti film in a vacuum without breaking vacuum, it ispossible to avoid the formation of a native oxide film on the surface ofthe Al film or on the surface of Si that has been precipitated on thesurface of the Al film, thus dispensing with a step of removing thenative oxide film.

It is possible to obtain almost the same effect even if the substrate isheated after the formation of the Al film and then a Ti film is formed.If the absorption of Si into the Ti film takes a longer time as comparedwith the time for forming the Ti film, the substrate may be additionallyheat-treated in an electric furnace after the deposition of the Ti filmon a heated substrate. When the substrate is heated prior to thedeposition of the Ti film to be functioned as an absorption film, the Alfilm can be thermally expanded, thus alleviating the stress.

EXAMPLE 12

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 16A to 16H.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate (not shown) provided with an element. This first wiring layer1 is partially separated from each other via an insulating film 2. Then,an interlayer insulating film 3 is formed all over the surface of the Sisubstrate (FIG. 16A).

Then, a Ti film 9 having a thickness of 200 nm is formed by means ofsputtering (FIG. 16B).

Thereafter, a resist pattern 21 is formed on the Ti film 9 by making useof lithography, and then the Ti film 9 and the interlayer insulatingfilm 3 are successively and selectively etched away thereby forming awiring groove 5 (FIG. 16C). In this process, a Cl-based gas is employedfor etching the Ti film 9 by means of the RIE method, while a F-basedgas is employed for etching the interlayer insulating film 3 by means ofthe RIE method. Subsequently, the resist pattern 21 is removed by ashingit (FIG. 16D).

Then, the interlayer insulating film 3 is selectively etched by RIEmaking use of a resist pattern 21 b as a mask to a depth reaching to thefirst wiring layer 1, thus forming a contact hole 4 (FIG. 16E). Namely,the contact hole 4 connected with the first wiring layer 1 and thewiring groove 5 is formed (FIG. 16F).

Then, a boron doped amorphous Si film 7 is deposited all over thesubstrate by means of LP-CVD method in a manner which makes it possibleto prevent any void from generating in the interior of the contact hole4. Then, the Si film 7 is selectively etched away by means of the CDEmethod so as to leave the Si film 7 only in the interior of the contacthole 4 (FIG. 16G).

Then, the native oxide film and impurities on the surfaces of the Tifilm 9 and Si film 7 deposited on the interlayer insulating film 3 areremoved by means of Ar ion sputtering, and then an Al film 8 is formedon the entire surface of the Si film 7 in a vacuum without breakingvacuum (FIG. 16H).

Thereafter, the substrate is heat-treated in an electric furnace for onehour at a temperature of 450° C., whereby allowing the Si film to besubstituted by the Al film and at the same time allowing asilicide-forming reaction to take place between the Si film and the Tifilm. Through the formation of the Ti silicide, the Si is absorbed bythe Ti film 9. In this step, an AlTi layer is also formed in addition tothe Ti silicide film, as indicated by the reference numeral 10 (FIG.16G).

Finally, the Al film formed outside of the wiring groove, Ti film, theTi silicide layer and the AlTi compound layer are all removed by meansof the CMP method. As a result, an Al plug 8 a and an AL wiring layer (asecond wiring layer) 8 b both consisting of the Al are formed in theinteriors of the contact hole and the wiring groove, respectively (FIG.16H).

In the explanation of Example 10, a method of arraying a plurality of Tifilm inside the Al film has been explained. However, the Ti film may bearrayed in plurality at the bottom of the Al film as illustrated in thisexample, thereby enhancing the trap efficiency of the Si atoms. Sincethe patterning of Ti film can be performed simultaneous with theformation of the wiring groove according to this example, the employmentof a shadow mask for the patterning of Ti film as in the case of Example10 is no more required, thus making it possible to minimize the peel-offof Ti dust from the shadow mask, which may otherwise become a problem inactual use.

When the Ti film is formed on the Al film, the generation of void maysometimes be recognized in the first Al wiring, in the interior ofcontact hole, or in the interior of the second Al wiring layer duringthe heat treatment for effecting the substitution between Si and Al andeffecting the absorption of Si by the upper Ti layer. The cause for thegeneration of such a void may be ascribed to the stress gradient thatmay be brought about by a change in volume of the AlTi alloy layer to beformed at the interface of Ti/Al or of the TiSi layer to be formed bythe absorption of Si. Namely, the void is generated for alleviating thestress being applied to the Al layer, and caused to remain in the firstAl wiring or in the interiors of contact hole or the second Al wiringlayer even after the Al film disposed outside of the wiring groove isremoved. The presence of void inside the wiring invites a cause for thedisconnection of wiring or the deterioration in reliability of wiring,thus necessitating some countermeasures.

In the case of Example 10, the Ti layer is not existed on the surface ofthe uppermost Al film, so that the Al film is not restrained by the TiSilayer or by the AlTi layer. In this case, although the bottom side ofthe Al film would be inflicted by a stress from the volume changeresulting from the TiSi reaction or from the AlTi alloy-formingreaction, the surface of the Al layer is free to deform, thus making itpossible to alleviate the stress and hence to prevent the void fromgenerating in the wiring groove, contact hole and first Al wiring layer.

This example is featured in that the Ti film which is capable ofabsorbing Si in the form of a silicide is formed at the bottom of the Alfilm. When this Ti film is disposed at the bottom of the Al film, thesurface of the Al film would not be restrained by the TiSi layer or AlTilayer. In this case, although the bottom side of the Al film would beinflicted by a stress from the volume change resulting from the TiSireaction or from the AlTi alloy-forming reaction, the surface of the Allayer is free to deform, thus making it possible to alleviate the stressand hence to prevent the void from generating in the wiring groove,contact hole and first Al wiring layer.

In the foregoing explanation of this example, a method of forming thewiring groove and contact hole, and concurrently filling them with Alhas been discussed. However, it is also possible to fill only thecontact hole with Al by making use of the aforementioned method.Specifically, a Ti film is formed all over the surface of an insulatingfilm, and the patterning of the Ti film and the insulating film isperformed by making use of photolithography and RIE (FIG. 17A). Then, anSi film is deposited all over the substrate, and then etch-backed bymeans of the CDE method, thereby leaving the Si film only in theinterior of the contact hole (FIG. 17B). Then, an Al film is depositedall over the surface of the resultant substrate (FIG. 17C). Under thiscondition, a heat treatment is performed, thereby causing the Si in thecontact hole to be absorbed in the form of silicide by the Ti filmformed on the insulating film, and at the same time the substitutionbetween the Si and Al is allowed to proceed (FIG. 17D). Finally, the Alfilm and the AlTi compound layer/TiSi compound/Ti layer are removed bymeans of the CMP method (FIG. 17E).

As explained above, in the case where an Al plug is formed in advance,an interlayer insulating film is then formed and a wiring groove isformed in the interlayer insulating film to a depth reaching to the Alplug, thus making it possible, by allowing the wiring groove to befilled with a low resistance metal such as Cu, to realize wiring.

EXAMPLE 13

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 18A to 18D.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole, and at the same time a wiringgroove is selectively formed likewise at a region including this contacthole. Namely, the contact hole connected with the first wiring layer 4and the wiring groove are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer 1 which has been exposed on the bottom of the contact holeis removed by means of a surface treatment. Then, an Si film 7 isdeposited all over the substrate by means of CVD method in a mannerwhich makes it possible to prevent any void from generating in theinteriors of the contact hole and the wiring groove, thus obtaining theSi film 7 exhibiting an excellent step coverage. Then, the Si film 7 isselectively removed by means of the CMP method or CDE method so as toleave the Si film 7 only in the interiors of the contact hole and thewiring. groove, thus removing any superfluous portion of the Si film 7(FIG. 18A).

Then, the native oxide film formed on the surface of the Si film 7 isremoved by means of a wet type surface treatment or a dry type surfacetreatment such as a reverse sputtering, and then an Al film 81 isdeposited all over the upper surface of the resultant substrate.Thereafter, the substrate is transferred to a separate chamber withoutbreaking vacuum and Ti fine particles are sprayed on the substrate bymaking use of a shower head type nozzle or any number of nozzle, therebydepositing a Ti layer. Then, Al is entirely deposited without breakingvacuum by means of sputtering method thereby forming an Al film 82containing the Ti fine particles (FIG. 18B).

In this case, it is also possible to form the Al film 82 by feeding theTi fine particles in concurrent with the sputtering of Al all over thesurface of the Al film 81.

It is also possible to form the Al film 82 by feeding a mixture of Tifine particles and Al fine particles all over the surface of the Al film81.

It is also possible to form the Al film 82 by coating a solutioncontaining a uniform dispersion of Ti fine particles and Al fineparticles all over the surface of the Al film 81.

Further, it is also possible to form the Al film 82 by a sputteringmethod where a target comprising Al and Ti fine particles buried the Alis employed. In this method, the Ti fine particles in the target wouldfall on the substrate to be entrapped by an Al film, thereby enabling anAl film containing a plurality of Ti film 9 a to be obtained as in thecase of the aforementioned method, but without employing anysophisticated sputtering apparatus.

It is also possible to employ a magnetron sputtering wherein the erosionregion (a region where plasma density is high) of the surface of targetis fixed, and any Ti particles re-adhered around the erosion region areallowed to fall onto the substrate, thereby dispersing them in the Alfilm together with the sputtered Ti.

It is also possible to employ a target having a roughened surface, andany Ti particles re-adhered to the roughened surface are allowed to fallonto the substrate, thereby dispersing them in the Al film together withthe sputtered Ti.

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilms 81 and 82, and at the same time allowing the Si film 7 to bereacted with the Ti fine particles in the Al film 82 to form a Tisilicide compound, thereby allowing the Si film 7 to be absorbed by theTi fine particles. During this step, a Ti/Ti silicide film 10 is formed(FIG. 18C).

Since the Ti fine particles functioning as an absorbent are dispersed inthe Al film 82, the area of Ti film to be reacted with Si is enlarged,thus making it possible to effectively turn the Si film 7 into a Tisilicide. Therefore, the substitution/absorption process in FIG. 18C canbe made high in efficiency.

Finally, the Ti/Ti silicide film 10 and any superfluous portion of theAl films 81 and 82 are all removed by means of the CMP method. As aresult, an Al plug and an Al wiring layer (a second wiring layer) bothconsisting of the Al film 8 are formed in the interiors of the contacthole and the wiring groove, respectively.

In the explanation of Examples 10 and 11, a method of forming an Al filmcontaining plural Ti films after the deposition of the Al film on the Sifilm, or a method of forming an Al film containing Ti fine particlesafter the deposition of the Al film on the Si film has been explained.However, if the contact hole and wiring groove are completely filledwith the Si film, it is also possible to obtain almost the same effecteven if a mixed film containing both Al and Ti is directly formed on theSi film.

Namely, when Ti is employed in a manner where a single layer of Ti ispartitioned into a plurality of sections, the surface area of the Tifilm to be contacted with Al can be increased, so that the effectivequantity of Ti useful for the absorption of Si per unit time can beincreased.

This invention is intended to obtain a buried type wiring, and hence ahigh resistance region comprising Ti or Ti compounds can be easilyremoved in the removing step employing the CMP in the step of forming awiring layer, thus making it possible to avoid an increase in resistanceof the wiring and at the same time to effectively promote thesubstitution reaction between Al and Si.

EXAMPLE 14

First of all, a first wiring layer consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating filmis formed all over the upper surface of the substrate.

Then, the interlayer insulating film is selectively etched by making useof photolithography and RIE to a depth reaching to the first wiringlayer, thus forming a contact hole, and at the same time a wiring grooveis selectively formed likewise at a region including this contact hole.Namely, the contact hole connected with the first wiring layer and thewiring groove are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer which has been exposed on the bottom of the contact hole isremoved by means of a surface treatment. Then, an Si film is depositedall over the substrate by means of CVD method in a manner which makes itpossible to prevent any void from generating in the interiors of thecontact hole and the wiring groove, thus obtaining the Si filmexhibiting an excellent step coverage. Then, the Si film is selectivelyremoved by means of the CMP method or CDE method so as to leave the Sifilm only in the interiors of the contact hole and the wiring groove,thus removing any superfluous portion of the Si film.

Then, the native oxide film formed on the surface of the Si film isremoved by means of a wet type surface treatment or a dry type surfacetreatment such as a reverse sputtering, and then an Al film is depositedall over the upper surface of the resultant substrate. Thereafter, thesubstrate is transferred to a separate chamber without breaking vacuum,and then a mixed film consisting of Al and Ti (an Al/Ti mixed film) isdeposited on the surface of the Al film by means of sputtering methodemploying a Ti target having Al pellets buried therein (a mosaictarget).

Thereafter, the substrate is heat-treated for one hour at a temperatureof 450° C. for instance, whereby allowing the Si film to be substitutedby the Al film and the Al/Ti mixed film, and at the same time allowingthe Si film to be reacted with the Ti in the Al/Ti mixed film to form aTi silicide compound, thereby allowing the Si film to be absorbed by theAl/Ti mixed film. During this step, a Ti/Ti silicide film is formed.

Finally, the Ti/Ti silicide film and any superfluous portion of the Alfilm and Al/Ti mixed film are all removed by means of the CMP method. Asa result, an Al plug and an Al wiring layer (a second wiring layer) bothconsisting of the Al film are formed in the interiors of the contacthole and the wiring groove, respectively.

In the explanation of this example, the Al/Ti mixed film is formed afterthe deposition of the Al film on the Si film. However, if the contacthole and wiring groove are completely filled with the Si film, the Al/Timixed film may be directly formed on the Si film.

Because, since the Si in the contact hole and wiring groove issubstituted through the heat treatment by the Al in the Al/Ti mixed filmdisposed over the Si, a silicide that brings about an increase inresistance is not formed in the interiors of the contact hole and wiringgroove to be employed as an electrode.

EXAMPLE 15

First of all, a first wiring layer consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating filmis formed all over the upper surface of the substrate.

Then, the interlayer insulating film is selectively etched by making useof photolithography and RIE to a depth reaching to the first wiringlayer, thus forming a contact hole, and at the same time a wiring grooveis selectively formed likewise at a region including this contact hole.Namely, the contact hole connected with the first wiring layer and thewiring groove are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer which has been exposed on the bottom of the contact hole isremoved by means of a surface treatment. Then, an Si film is depositedall over the substrate by means of CVD method in a manner which makes itpossible to prevent any void from generating in the interiors of thecontact hole and the wiring groove, thus obtaining the Si filmexhibiting an excellent step coverage. Then, the Si film is selectivelyremoved by means of the CMP method or CDE method so as to leave the Sifilm only in the interiors of the contact hole and the wiring groove,thus removing any superfluous portion of the Si film.

Then, the native oxide film formed on the surface of the Si film isremoved by means of a wet type surface treatment or a dry type surfacetreatment such as a reverse sputtering, and then an Al film and a Tifilm are deposited all over the upper surface of the resultant substratewithout breaking vacuum.

Thereafter, the substrate is subjected to a heat treatment under thetemperature sequence as shown in FIGS. 19A to 19C. For example, thesubstrate is heat-treated for 30 minutes at a temperature of 500° C.thereby allowing a substitution reaction to take place between the Sifilm and the Al film, and then heat-treated again for two hours at atemperature of 450° C. and then for 10 hours at a temperature of 430° C.(FIG. 19 A).

As a result of this multi-stage heat treatment, the Si film can besubstituted by the Al film, and at the same time the Si film is allowedto be reacted with the Ti film to form a Ti silicide compound, therebyallowing the Si film to be absorbed by the Ti film. During this step, aTi/Ti silicide film is formed.

Finally, the Ti/Ti silicide film and any superfluous portion of the Alfilm are all removed by means of the CMP method. As a result, an Al plugand an Al wiring layer (a second wiring layer) both consisting of the Alfilm are formed in the interiors of the contact hole and the wiringgroove, respectively.

According to this invention, it is possible with the employment of thismulti-stage heat treatment to shorten the substitution time between thesubstitutive film (Si film) and the conductive film (Al film) as well asthe absorption time of the substitutive film (Si film) by the absorptionfilm (Ti film), and at the same time to lower the resistance of theconductive film (Al film) remaining in the wiring groove and contacthole.

Specifically, if an Si film is employed as a substitutive film, an Alfilm as a conductive film, and a Ti film as an absorption film, themutual diffusion between Al and Si as well as the absorption. reaction(silicifying reaction) take place vigorously at a temperature of 400° C.or more. Therefore, as far as the substitution and the absorption areconcerned, the higher the heat treatment temperature is, the shorter thetime that will be required.

However, the solid solution limit of Si in the Al film changes accordingto temperature, i.e. the higher the temperature is, the larger the solidsolution limit of Si is. Accordingly, when the solid solution quantityof an impurity in the Al film is increased, the resistance of the Alfilm would be increased, and hence the wire resistance would increased,thus raising a problem.

In order to overcome this problem, a low temperature heat treatment isperformed after allowing the substitution and the absorption to takeplace at a high temperature heat treatment, thus discharging the Si toan extent of the solid solution limit of Si in the Al film at lowtemperature. Therefore, it is possible according to this invention torealize not only the shortening of the substitution/absorption time, butalso the lowering of resistance.

The multi-stage heat treatment is not limited to a three-stage heattreatment as explained in this example, but it may be a two-stage heattreatment or a four or more-stage heat treatment. Furthermore, almostthe same effect for lowering the wire resistance can be obtained even ifa temperature sequence where the temperature is raised or lowered at themiddle as shown in FIG. 19B is employed as long as the final heattreatment temperature is lower than the preceding heat treatmenttemperatures.

It is also possible to obtain almost the same effect of lowering thewire resistance, even if the heat treatment is not constituted by astep-wise temperature changes, but is constituted by a gradual cooling(FIG. 19C).

EXAMPLE 16

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 20A to 20F.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film 3. Then, a native oxide film formed on theupper surface of the first wiring layer 1 which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

Then, an Si film 7 is deposited all over the substrate by means of CVDmethod in a manner which makes it possible to prevent any void fromgenerating in the interiors of the contact hole and the wiring groove.Then, the Si film 7 is selectively removed by means of the CMP method soas to leave the Si film 7 only in the interiors of the contact hole andthe wiring groove 5, thus removing any superfluous portion of the Sifilm 7.

Then, the native oxide film formed on the surface of the Si film 7 isremoved, and then an Al film 81 and a Ti layer 91 successively depositedwithout breaking vacuum (FIG. 20A).

Thereafter, the substrate is heat-treated for 30 minutes at atemperature of 450° C., whereby allowing the Si film 7 to be substitutedby the Al film 81, and at the same time allowing the Si film 7 to bereacted with the Ti 91 to form a Ti silicide compound, thereby allowingthe Si film 7 to be absorbed by the Ti 91. During this step, a Ti/Tisilicide film 101 is formed (FIG. 20B).

Then, the Ti/Ti silicide film 101 and any superfluous portion of the Alfilm 81 are all removed by means of the CMP method (FIG. 20C).

Then, an Al film 82 and a Ti layer 92 are successively deposited allover the resultant substrate as in the case of the Al film 81 and the Tilayer 91 (FIG. 20D).

Thereafter, the substrate is heat-treated for 30 minutes at atemperature of 450° C., whereby allowing the Si remaining in the wiringgroove and contact hole to be removed again (FIG. 20E). During thisstep, a Ti/Ti silicide film 102 is formed.

Finally, the Ti/Ti silicide film 102 and any superfluous portion of theAl films 81 and 82 disposed outside the wiring groove are all removed bymeans of the CMP method (FIG. 20F).

As a result, an Al plug and an Al wiring layer (a second wiring layer)both consisting of the Al film are formed in the interiors of thecontact hole and the wiring groove, respectively.

In the foregoing explanation, the absorption of Si remaining in the Alfilm filled in the wiring groove is performed by a process wherein theAl film 82 and Ti layer 92 are successively deposited again andheat-treated after the removal of the Ti/Ti silicide film 101 and asuperfluous portion of the Al film 81 disposed outside of the wiringgroove. However, it is also possible to adopt a process wherein theTi/Ti silicide film 101 is removed in such a manner that the Al film 81is left remained in the interior of the wiring groove and in a regionoutside the wiring groove, and then only the Ti layer 92 is depositedentirely whereby re-absorbing the Si left remained in the Al film 81filled in the wiring groove.

EXAMPLE 17

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 21A to 21D.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film 3. Then, a native oxide film formed on theupper surface of the first wiring layer 1 which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

Then, an Si film 7 is deposited all over the substrate by means of CVDmethod in a manner which makes it possible to prevent any void fromgenerating in the interiors of the contact hole and the wiring groove.

Then, the Si film 7 is selectively removed by means of the CMP method soas to leave the Si film 7 only in the interiors of the contact hole andthe wiring groove 5, thus removing any superfluous portion of the Sifilm 7.

Then, the native oxide film formed on the surface of the Si film 7 isremoved, and then an Al film 8 c which is free form impurities is formedand then a Ti layer 9 c containing Cu 13 is deposited without breakingvacuum (FIG. 21A). In this case, the Ti layer 9 c containing Cu 13 canbe obtained for instance by means of sputtering method employing a Titarget containing Cu.

Thereafter, the substrate is heat-treated for two hours at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilm 8 c, and at the same time the Cu 13 included in the Ti film 9 c isallowed to diffuse into the Al film 8 c. At the same time, the Si film 7is allowed to react with the Ti film 9 c to form a Ti silicide compound,thereby allowing the Si film 7 to be absorbed by the Ti film 9 c. Duringthis step, a Ti/Ti silicide film 10 c and a Cu silicide 10 d is formed(FIGS. 21B and 21C).

Finally, the Ti/Ti silicide film 10 c, the Cu silicide 10 d and anysuperfluous portion of the Al film 8 c disposed outside the wiringgroove are all removed by means of the CMP method.

As a result, an Al plug and an Al wiring layer (a second wiring layer)both consisting of the Al film are formed in the interiors of thecontact hole and the wiring groove, respectively (FIG. 21D).

Since the Cu 13 is included in the Al film 8 c in thesubstitution/absorption step of FIG. 21C according to this example, thesolid solution limit of Si in the Al film 8 c at the same temperaturecan be lowered than that in the Al film to which Cu 13 is not added.Therefore, it is possible according to this-example to achieve thelowering of wire resistance even if the substitution/absorptiontreatment is performed at a relatively high temperature.

The addition of Cu can be performed by depositing a Cu film after theformation of a silicide, and then by re-heating the Cu film, therebyobtaining almost the same effect. The Cu film may be formed on thesurface of the Ti film, at the interface between the Ti film and Alfilm, or on the bottom of the Al film. Alternatively, Cu may beintroduced into the Al film.

In the foregoing explanation, Cu is employed as a material for loweringthe solid solution limit of Si in the Al film. However, it is alsopossible to employ other kinds of material as long as the material doesnot invite an increase in resistance as compared with Si when thematerial in introduced into the Al film. In this case, the material maynot be a single substance but may be formed of plural kinds of element.

Since Cu is prone to diffuse into an insulating film such as SiO₂, ifthe Cu film is to be formed on the bottom of the Al film, it may beadvisable to form a barrier film on the surface of the insulating filmfor the purpose of preventing the diffusion of Cu.

EXAMPLE 18

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 22A to 22E.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film 3. Then, a native oxide film formed on theupper surface of the first wiring layer 1 which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

Then, a TiN film 14 is deposited as a barrier. layer all over thesubstrate. Thereafter, an Si film 7 is deposited all over the substrateby means of CVD method so as to fill the interiors of the contact holeand the wiring groove with the Si film 7.

Then, a superfluous portion of the Si film 7 is selectively removed bymeans of CDE etch-back method or RIE etch-back method so as to leave theSi film 7 only in the interiors of the contact hole and the wiringgroove 5.

Then, the native oxide film formed on the surface of the Si film 7 isremoved, and then an Al film 8 c which is free form impurities is formedand then a Ti layer 9 c is deposited without breaking vacuum (FIG. 22A).

Thereafter, the substrate is heat-treated for two hours at a temperatureof 450° C., whereby allowing the Si film 7 to be substituted by the Alfilm 8 c, and at the same time the Si film 7 is allowed to react withthe Ti film 9 to form a Ti silicide compound, thereby allowing the Sifilm 7 to be absorbed by the Ti film 9. During this step, a Ti/Tisilicide film 10 c and a Cu silicide 10 d are formed (FIG. 22B).

Then, the Ti/Ti silicide film 10 c and any superfluous portion of the Alfilm 8 c disposed outside the wiring groove are all removed by means ofthe CMP method.

As a result, an Al plug and an Al wiring layer (a second wiring layer)both consisting of the Al film 8 c are formed in the interiors of thecontact hole and the wiring groove, respectively (FIG. 22C).

Then, a Cu film 15 is deposited all over the substrate and thenheat-treated for 5 minutes at a temperature of 300° C. thus renderingthe Cu 13 in the Cu film 15 to diffuse into the Al film 8 c (FIG. 22D).

Finally, the Cu film 15 and any superfluous portion of the TiN film 14are removed by means of CMP method (FIG. 22E).

The Cu 13 added to the Al film 8 c is a material which capable ofimproving the electromigration resistance as well as the stressmigration resistance. Namely, in the phenomenon of these migrations, theCu in the Al wiring is precipitated at the crystal boundary where thediffusion rate of Al is very fast, whereby inhibiting the grain boundarydiffusion of Al. Because of this effect, about 0.5% by weight of Cu isgenerally added in advance to the Al wiring of the recent LSI.

The manufacture of Cu-containing Al film can be performed generally bymaking use of a sputtering method employing a Cu-containing Al target.

Cu is well known as a material which capable of reacting with Si at alow temperature thereby forming a silicide compound.

Therefore, if an Al film added in advance with Cu is employed as aconductive film in contrast to this example, the Si constituting thesubstitutive film is absorbed not only by the Ti film but also by the Cuin the Al film functioning as the conductive film, thus generating areaction product of Si and Cu, such as a Cu silicide.

If the contact hole and the wiring groove are to be completely filledwith the Si film 7 in contrary to this example, the reaction productformed through the absorption of Si by the Cu in the Al film would beformed outside of the wiring groove. Therefore, it can be removed at thestep of removing the Ti/Ti silicide film 10, thus raising no problem.

However, when only the interior of contact hole is filled with Si, andthe interior of the wiring groove is not filled with Si as in the caseof this example, the reaction product to be formed through theabsorption of Si by the Cu in the Al film would be formed also in theinterior of the wiring groove.

Therefore, the reaction product cannot be removed at the step ofremoving the Ti/Ti silicide film 10.

Accordingly, if only the interior of contact hole is to be filled withSi, it is advisable to form an Al film 9 c which is free from anyimpurities (a pure Al) as a conductive film, and then to add Cu to theAl film 9 c.

EXAMPLE 19

First of all, a first wiring layer is formed on an Si substrate providedwith an element. Then, an interlayer insulating film is formed all overthe upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film. Then, a native oxide film formed on theupper surface of the first wiring layer which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

Then, an Si film is deposited all over the substrate by means of CVDmethod so as to fill the interiors of the contact hole and the wiringgroove with the Si film.

Then, a superfluous portion of the Si film is selectively removed bymeans of CMP method so as to leave the Si film only in the interior ofthe contact hole.

Then, the native oxide film formed on the surface of the Si film isremoved, and then an Al film and a Co film are successively depositedwithout breaking vacuum.

Thereafter, the substrate is heat-treated for 30 minutes at atemperature of 400° C., whereby allowing the Si film to be substitutedby the Al film, and at the same time the Si film is allowed to reactwith the Co film to form a Co silicide compound, thereby allowing the Sifilm to be absorbed by the Co film.

Finally, the Co/Co silicide film and any superfluous portion of the Alfilm are all removed by means of the CMP method. As a result, an Al plugand an Al wiring layer (a second wiring layer) both consisting of the Alfilm are formed in the interiors of the contact hole and the wiringgroove, respectively.

The Co film employed in this example as an absorption film is capable ofeffectively substituting and absorbing the Si film being formed as asubstitutive film at the diffusion temperature range of Si in the Alfilm to be employed as a conductive film.

This is because the Co film is capable of generating a silicifyingreaction at a lower temperature as compared with Ti film which has beenexemplified as an absorption film in the previous examples. Therefore,if a combination of materials including Co is employed, the substitutioncan be performed with a heat treatment of lower temperature.

Furthermore, when the heat treatment is performed at a highertemperature, the reaction of forming a silicide can be accelerated andhence the substitution time can be shortened as compared with where a Tifilm is employed.

The Co film employed in this example is merely one example of anabsorption film having such a property. For example, an absorption filmconsisting of Fe can be employed likewise. Namely, when theaforementioned heat treatment is performed using these absorption filmsat a temperature range which enables Si to diffuse into an Al film andat the same time enables the silicifying reaction to take place withthese absorption films, the substitution and absorption efficiencieswhich are more than comparable. with those where a Ti film is employedcan be obtained.

Further, when a Ge film or an Si/Ge mixed film is employed as asubstitutive film, the interdiffusion thereof with an Al film can betaken place at a lower temperature as compared with where an Si film isemployed. Namely, since the diffusion temperature of the constituentelement of the substitutive film in an Al film can be lowered, thetemperature for the substitution/absorption reaction can be lowered, andat the same time, the time required for the substitution/absorptionreaction can be shortened.

In the present example, a combination of the materials by which thesubstitution temperature can be lowered or the substitution time can beshortened as compared with Ti is employed. However, the presentinvention is not limited to these materials in the case of the processtemperature permitted in the other process. For example, Hf, V, Mo, W,Ta, Nb, Zr, or the like is effective in the same manner as Ti.

EXAMPLE 20

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to FIGS. 23A to 23D.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole 4, and at the same time a wiringgroove 5 is selectively formed likewise at a region including thiscontact hole 4. Namely, the contact hole 4 connected with the firstwiring layer 1 and the wiring groove 5 are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer 1 which has been exposed on the bottom of the contact hole4 is removed by means of a surface treatment. Then, an Si film 7 isdeposited all over the substrate by means of CVD method in a mannerwhich makes it possible to fill the interiors of the contact hole 4 andthe wiring groove 5 with the Si film 7. Then, any superfluous portion ofthe Si film 7 is selectively removed by means of the CMP method or CDEmethod so as to leave the Si film 7 at least in the interior of thecontact hole 4.

Then, the native oxide film formed on the surface of the Si film 7 isremoved, and then an Al film 8. is deposited all over the upper surfaceof the resultant substrate. Thereafter, an Al film 22 is deposited onthe Al film 8 by means of a bias sputtering method in the same manner asexplained in Example 4 (FIG. 23A). The Al film 22 to be formed by meansof the bias sputtering method is deposited under the conditions whichenable a rare gas, crystal defects or impurities to be included in andsustained by the resultant Al film.

Then, through a heat treatment, the Si filled in the interiors of thecontact hole 4 and the wiring groove 5 is caused to diffuse into the Alfilm (FIG. 23B) and hence to be substituted by Al. At the same time, theSi filled in the interiors of the contact hole 4 and the wiring groove 5is caused to be segregated at the upper portion of Al film, inparticular a porous Al film portion (FIG. 23C).

As shown in Example 11, the Si filled in the interiors of the contacthole and the wiring groove is caused, through a substitution heattreatment, to be substituted by Al and at the same time, to bedischarged or segregated out of the contact hole and the wiring groove.This reaction takes advantage of the phenomenon that the interfacebetween Al/vacuum can make the segregated Si lower in surface energy andmore stable as compared with the interior of the Al film or with theinterface between Al/oxide film constituting the contact hole or thewiring groove.

Furthermore, according to this example, a precipitation-promoting layer22 is intentionally formed on the surface of the Al film, therebycausing Si to segregate on the precipitation-promoting layer 22 whileallowing the substitution reaction to proceed. As a result, aconcentration gradient of Si is caused to generate in the Al film, sothat even if. Si is existed in a large amount in the pattern, the Si canbe sufficiently discharged from the pattern.

Further, even if all of Si disposed outside of the contact hole orwiring groove is formed by means of bias sputtering, the Al to be filledin the pattern can be turned, through the substitution reaction, into anAl wiring or an Al plug each having a sufficiently high density as awiring layer since the substitution reaction between the Si and the Alis based on the mutual diffusion between the individual Al atom and theindividual Si atom as mentioned in Example 4, the residual upper portionof the Al being utilized as a gettering layer for the Si. Since thisresidual portion of the Al is. ultimately removed, almost the sameeffect as obtained in the previous example can be obtained.

Since there is no possibility of change in volume of the upper Al layerportion that might be caused by the formation of a TiSi compound or dueto the formation of an AlTi compound in contrast to the structure wherea Ti layer is formed on the upper surface of the Al film, no stresswould be imposed on the Al film.

In this example, an Al layer formed by means of bias sputtering isexemplified as an Si precipitation-promoting layer. However, it is alsopossible to obtain almost the same effect even if an ion-implanted Alfilm is employed.

EXAMPLE 21

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to the same FIGS. 23A to 23Dwhich have been employed for the explanation of Example 20.

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole 4, and at the same time a wiringgroove 5 is selectively formed likewise at a region including thiscontact hole 4. Namely, the contact hole 4 connected with the firstwiring layer 1 and the wiring groove 5 are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer 1 which has been exposed on the bottom of the contact hole4. is removed by means of a surface treatment. Then, an Si film 7 isdeposited all over the substrate by means of CVD method in a mannerwhich makes it possible to fill the interiors of the contact hole 4 andthe wiring groove 5 with the Si film 7. Then, any superfluous portion ofthe Si film 7 is selectively removed by means of the CMP method or CDEmethod so as to leave the Si film 7 at least in the interior of thecontact hole 4.

Then, the native oxide film formed on the surface of the Si film 7 isremoved, and then an Al film 8 and a W film 22 are deposited all overthe upper surface of the resultant substrate (FIG. 23A).

Then, through a heat treatment, the Si filled in the interiors of thecontact hole 4 and the wiring groove 5 is caused to diffuse into the Alfilm (FIG. 23B) and hence to be substituted by Al. At the same time, theSi filled in the interiors of the contact hole 4 and the wiring groove 5is caused to be segregated at the interface between W/Al films or at thegrain boundary of W (FIG. 23C).

In this example, a film using a different material from that of thesubstitutive film is employed. as a precipitation-promoting layer 22. Aslong as the material is hardly reactive to Al at the temperature of thesubstitution heat treatment, the material can be employed as aprecipitation-promoting layer 22. In this case, the W film 22functioning a precipitation-promoting layer 22 can be arranged anywherewithin the Al film 7. Namely, it may be disposed at the bottom, in themiddle or on the upper surface of the Al film 7. Further, the depositionmethod of the W film 22 is not confined to the CVD method and sputteringmethod.

It is also possible to utilize the Si constituting the substitutive filmas a precipitation-promoting layer. Namely, since the solid solutionlimit of Si in Al film is determined by the temperature, if Si is formedto have a sufficient volume, the Si segregated acts to minimize itssurface area in relative to the volume thereof, whereby causing aregional precipitation to take place as a precipitation-promoting layerand hence generating a concentration gradient of Si to promote thesubstitution between Al and Si.

EXAMPLE 22

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to the same FIGS. 24A to 24 C.

First of all, a first wiring layer 1 is formed on an Si substrateprovided with an element. Then, an interlayer insulating film 3 isformed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film 3. Then, a native oxide film formed on theupper surface of the first wiring layer 1 which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

After a W—Si—N film 16 is deposited all over the substrate, an Nb film17 is deposited all over the substrate so as to fill the interiors ofthe contact hole and the wiring groove 5 with the Nb film 17.

Then, any superfluous portion of the Nb film 17 is selectively removedby means of the CMP method so as to leave the Nb film 17 in theinteriors of the contact hole and wiring groove.

After the native oxide film formed on the surface of the Nb film 17 isremoved, a Cu film 15 is deposited all over the upper surface of theresultant substrate (FIG. 24A).

Then, through a heat treatment in a vacuum, the Cu film 15 issubstituted for the Nb film 17, and at the same time, Nb is allowed tosegregate on the surface of the Cu film 15 (upper surface) and at theinterface between the Cu film 15 and the W—Si—N film 16 (FIG. 24B).

Finally, the Nb film 17 and any superfluous portion of the Cu film 15are removed by means of CMP method (FIG. 22E). As a result, a Cu plugand a Cu wiring layer (a second wiring layer) both consisting of the Cufilm are formed in the interiors of the contact hole and the wiringgroove, respectively (FIG. 24C).

Although the heat treatment is performed in a vacuum in this example, agaseous atmosphere comprising an N₂ gas, an N₂/H₂ mixed gas or an NH₃gas may be employed in the heat treatment.

In this case, NbN is allowed to segregate on the surface of the Cu film15 (upper surface) and at the interface between the Cu film 15 and theW—Si—N film 16. As a result, as shown in FIG. 24D, an NbN film 18 isformed on the surface (upper surface) of the Cu film 15, while a mixedfilm 19 consisting of NbN and Nb is formed at the interface.

The heat treatment may be performed in the plasma or radicals of an N₂gas, an N₂/H₂ mixed gas or an NH₃ gas. Ions and radicals are highlyreactive, so that the nitrization of the Nb film 17 can be facilitated.

When the upper surface or interface of the Nb film 17 is nitrided, theconcentration of the Nb film 17 is reduced on the upper surface sidethereof, thereby generating a concentration gradient of Nb in the Cufilm 15. As a result, the diffusion flux of Nb is induced to increase atthe surface region, thus rendering the diffusion/substitution betweenthe Cu film and the Nb film, as well as the precipitation of Nb on thesurface side to take place more efficiently.

These Nb and NbN segregate not only on the surface of the Cu film 15 butalso on the interface between the Cu film 15 and the contact hole orwiring groove (W—Si—N film 16 ), thereby forming a film comprising NbN.This film can be utilized as a barrier film for inhibiting the Cu in theCu film 15 from diffusing into the interlayer insulating film 3 or intothe substrate.

EXAMPLE 23

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to the same FIGS. 25A to 25C.

First of all, a first wiring layer 1 is formed on an Si substrateprovided with an element. Then, an interlayer insulating film 3 isformed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film 3. Then, a native oxide film formed on theupper surface of the first wiring layer 1 which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

Then, an Nb film 17 is deposited all over the substrate by means of CVDmethod so as to fill the interiors of the contact hole and the wiringgroove 5 with the Nb film 17.

Then, any superfluous portion of the Nb film 17 is selectively removedby means of the CMP method so as to leave the Nb film 17 in theinteriors of the contact hole and wiring groove (FIG. 25A).

Then, a Cu film 15 is deposited all over the upper surface of theresultant substrate by making use of a directional sputtering method soas to fill the interior of the wiring groove with the Cu film 15. Thewiring groove may be filled with the Cu film 15 by means of CVD methodinstead of employing the aforementioned directional sputtering method.Subsequently, any superfluous portion of the Cu film 15 is removed bymeans of CMP method so as to leave the Cu film 15 only in the wiringgroove (FIG. 25B).

It is possible in the above step to employ a selective CVD method forfilling the wiring groove with the Cu film 15. In this case, a step ofremoving a superfluous portion of the Cu film 15 can be dispensed with.It is also possible to preliminarily fill at least the interior of thewiring groove with a conductive film for the purpose of facilitating theselective deposition of the Cu film 15. Depending on the material to beemployed, this conductive material can be utilized also as a metallicbarrier film.

Then, through a heat treatment in a vacuum, the Cu film 15 issubstituted for the Nb film 17, and at the same time, Nb is allowed tosegregate on the surface of the Cu film 15, thereby forming the Nb film17 on the surface of the Cu film 15 (FIG. 25C).

Although the heat treatment is performed in a vacuum in this example, agaseous atmosphere comprising an N₂ gas, an N₂/H₂ mixed gas or an NH₃gas may be employed in the heat treatment. The heat treatment can bealso performed in the plasma or radicals of an N₂ gas, an N₂/H₂ mixedgas or an NH₃ gas. Ions and radicals are highly reactive, so that thesurface of Nb film 17 can be nitrided to easily form a surface-nitridedNb film (NbN film).

The Nb film as well as the surface-nitrided Nb film (NbN film) thusformed can be utilized as a barrier film for inhibiting the Cu in the Cufilm 15 from diffusing into the interlayer insulating film 3 or into theSi substrate.

EXAMPLE 24

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to the same FIGS. 26A to 26D.

First of all, a first wiring layer 1 consisting of Cu is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film 3. Then, a native oxide film formed on theupper surface of the first wiring layer 1 which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

Then, an Si film 7 is deposited all over the substrate by means of CVDmethod so as to fill the interiors of the contact hole and the wiringgroove 5 with the Si film 7.

Then, any superfluous portion of the Si film 7 is selectively removed bymeans of the CDE method so as to leave the Si film 7 in the interiors ofthe contact hole and wiring groove (FIG. 26A).

After the native oxide film formed on the surface of the Si film 7 isremoved, a Cu film 15 is deposited, without breaking vacuum, all overthe upper surface of the resultant substrate by means of a directionalsputtering method so as to fill the interior of the wiring groove withthe Si film 7 (FIG. 26B).

Then, through a heat treatment in an atmosphere containing oxygen (O₂),in an atmosphere of oxygen plasma (ions, radicals), or in an atmosphereof oxygen radicals, the Cu film 15 is substituted for the Si film 7, andat the same time, the Si atom of the Si film 7 which has been diffusedthrough the surface of the Cu film 15 is allowed to react with the O inthe aforementioned atmospheres to form SiO₂. As a result, a mixed film20 comprising Si and SiO₂ is formed on the surface of the Cu film 15(FIG. 26C).

Cu is highly reactive with Si, so that they are suited for use informing a silicide at a lower temperature. However, if these elementsare subjected to heat treatment in an atmosphere containing oxygen, Sibecomes more reactive and hence is reacted with oxygen, thusdissociating from Cu, to form SiO₂.

The Cu thus released is allowed, through the SiO₂-generating reaction atthe surface of the Cu film, to diffuse into the interiors of the contacthole and wiring groove, thus making it possible to fill the contact holeand wiring groove with Cu. The SiO₂-generating reaction at the surfaceof the Cu film may be conducted by a heat treatment in anoxygen-containing atmosphere, or in a plasma- or radical-containingatmosphere.

The heat treatment for effecting the substitution/diffusion may beperformed simultaneous with the aforementioned SiO₂-generating reactionat the surface of the Cu film. Alternatively, the silicifying reactionbetween Cu and Si in a non-oxidizing atmosphere or in a vacuum isallowed to take place at first, and then Si is removed from the Cu film15 through the formation of SiO₂ initiating from the surface region.

Finally, the mixed film 20 and any superfluous portion of the Cu film 15are removed by means of CMP method. As a result, a Cu plug and a Cuwiring layer (a second wiring layer) both consisting of the Cu film 15are formed in the interiors of the contact hole and the wiring groove,respectively (FIG. 26D).

EXAMPLE 25

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to the same FIGS. 27A to 27D.

First of all, a first wiring layer 1 consisting of Cu is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film 3. Then, a native oxide film formed on theupper surface of the first wiring layer 1 which has been exposed on thebottom of the contact hole is removed by means of a surface treatment.

Then, a W film 21 is deposited all over the substrate by means of aselective CVD method so as to fill the interior of the contact hole withthe W film 21 (FIG. 27A). After the native oxide film formed on thesurface of the W film 21 is removed, a Cu film 15 is deposited, withoutbreaking vacuum, all over the upper surface of the resultant substrateby means of a directional sputtering method so as to fill the interiorof the wiring groove with the Si film 7 (FIG. 27B).

Then, through a heat treatment in an atmosphere containing CF₄, in anatmosphere of CF₄ plasma, or in an atmosphere of CF₄ radicals, the Cufilm 15 is substituted for the W film 21, and at the same time, the Watom of the W film 21 which has been diffused through the surface of theCu film 15 is allowed to react with the F in the aforementionedatmospheres to form WF₆ gas, thereby removing the W film 21 (FIG. 27C).

W is highly reactive with F, so that the vapor pressure of a tungstenfluoride compound is very high. This example takes advantage of thisphenomenon in the step of substitution, through diffusion, between Cuand W. Namely, F is fed from the surface side in this step thereby toform a WF₆ gas, which is then removed during the substitution heattreatment, thereby lowering the concentration of W on the surface regionand hence promoting the substitution reaction. Further, this method isadvantageous in that the step of removing a compound formed ultimatelyon the upper portions of the contact hole and wiring groove can bedispensed with.

Finally, any superfluous portion of the Cu film 15 disposed outside ofthe wiring groove is removed by means of CMP method. As a result, a Cuplug and a Cu wiring layer (a second wiring layer) both consisting ofthe Cu film 1 s are formed in the interiors of the contact hole and thewiring groove, respectively (FIG. 27D).

EXAMPLE 26

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to the same FIGS. 28A to 28H.

First of all, a first wiring layer consisting of a laminate filmcomprising a polysilicon film 22 and a tungsten film 23(tungsten/polyside film) is formed on an Si substrate (not shown)provided with an element.

Then, an interlayer insulating film 31 having a thickness of 0.8 μm andconsisting of Si is formed all over the upper surface of the substrateby making use of a plasma CVD method. Then, a first contact hole and afirst wiring groove are successively formed in the interlayer insulatingfilm 31 by making use of a photolithography and the RIE method (FIG.28A).

Then, a first Ti film 91 having a thickness of 20 nm is formed all overthe surface of the substrate, and subsequently a TiN film 14 having athickness of 10 nm is formed all over the surface of the resultantsubstrate by means of the MOCVD method.

In this step of forming the first Ti film 91, the employment of acollimation sputtering method or a low pressure-long distance sputteringmethod which are excellent in directivity is preferable in view ofobtaining a desired coverage at the bottom of the first contact hole.

Subsequently, an Si film 7 is formed all over the surface of thesubstrate by means of CVD method so as to fill the first contact holeand the first wiring groove with the Si film 7 (FIG. 28B).

Then, any superfluous portion of the Si film 7 is selectively removed bymaking use of the CDE method or CMP method so as to leave the Si film 7in the first contact hole and the first wiring groove (FIG. 28C).

Then, a second interlayer insulating film 32 is deposited all over thesubstrate by means of the plasma CVD method. Since the first contacthole and the first wiring groove are filled with the Si film 7 at thismoment, the method of forming the second interlayer insulating film 32may be carried out by means of LPCVD method in place of the plasma CVDmethod. Namely, an insulating film which can be formed at a hightemperature such as a BPSG film or a TEOS film (which can be formedmaking use of the LPCVD method) can be employed as this secondinterlayer insulating film 32.

Subsequently, a second contact hole and a second wiring groove aresuccessively formed in the second interlayer insulating film 32 bymaking use of a photolithography and the RIE method (FIG. 28D). Then, anative oxide film formed on the upper surface of the Si film 7 which hasbeen exposed on the bottom of the second contact hole is removed bymaking use of a dilute hydrofluoric acid.

Then, another Si film 7 is deposited all over the substrate by means ofCVD method so as to fill the interior of the second contact hole and thesecond wiring groove with the Si film 7. Thereafter, any superfluousportion of the Si film 7 is selectively removed by making use of the CDEmethod or CMP method so as to leave the Si film 7 in the second contacthole and the second wiring groove (FIG. 28E).

After the native oxide film formed on the surface of the Si film 7 isremoved by means of an Ar sputter-etching method, an Al film 8 having athickness of 2 μm and a second Ti film 92 having a thickness of 200 nmare successively deposited, without breaking vacuum, all over the uppersurface of the resultant substrate by means of a sputtering method (FIG.28F).

Thereafter, the substrate is heat-treated for three hours at atemperature of 450° C., whereby allowing the Si film 7 filled in thesecond contact hole and the second wiring groove to be substituted enbloc by the Al film 8, and at the same time the Si film 7 is allowed toreact with the Ti film 92 to form a Ti silicide compound, therebyallowing the Si film 7 to be absorbed by the Ti film 92. During thisstep a Ti/Ti silicide film 10 is formed (FIG. 28G).

According to this method, it is possible, even if the aspect ratio ofthe contact hole is high, to fill the contact hole as well as the wiringgroove with an Al film without generating voids therein.

Finally, the Ti/Ti silicide film 10 and any superfluous portion of theAl film 8 disposed outside of the second wiring groove are removed bymeans of CMP method.

As a result, a first Al plug and a first Al wiring layer (a secondwiring layer) both consisting of the Al film are formed in the interiorsof the first contact hole and the first wiring groove, respectively, andat the same time, a second Al plug and a second Al wiring layer (a thirdwiring layer) both consisting of the Al film are formed in the interiorsof the second contact hole and the second wiring groove, respectively(FIG. 28H).

Although not particularly pointed out in this example, if a large numberof the second contact hole are formed in the same layer, thesubstitution route between the Si film 7 and the Al film 8 can beincreased, thereby making it possible to lower the temperature in thesubstitution/absorption step and also to shorten the substitution time.

Although a method of performing simultaneous substitution of two layershas been explained in this example, it is also possible to perform asimultaneous substitution of three of more layers by repeating theformation of an Si film-filled wiring groove and an Si film-filledcontact hole three times or more, and by carrying out the substitutionheat treatment after successively depositing an Al film and a Ti film onthe uppermost layer of the laminate structure.

In this case however, since the consumption of Al film and Ti film wouldbe increased as compared. with the two-layer structure, the filmthickness of each of Al film and Ti film should preferably be increasedfor the purpose of reducing the wire resistance.

EXAMPLE 27

A method of manufacturing a semiconductor device according to thisexample will be explained with reference to the same FIGS. 29A to 29J.

First of all, a first wiring layer consisting of a laminate filmcomprising a polysilicon film 22 and a tungsten film 23(tungsten/polyside film) is formed on an Si substrate (not shown)provided with an element.

Then, an interlayer insulating film 3 having a thickness of 0.8 μm andconsisting of SiO₂ is formed all over the upper surface of the substrateby making use of a plasma CVD method. Then, a first contact holeconnected with the first wiring layer is formed in the interlayerinsulating film 3 by making use of a photolithography and the RIEmethod. Subsequently, a Ti film 9 having a thickness of 20 nm is formedby means of a directivity-enhanced low pressure-long distance sputteringmethod (FIG. 29A). Then, the substrate is heated to 550° C. to perform aheat treatment for 30 minutes in a forming gas atmosphere (N₂-10%H₂).Through this heat treatment, the surface of the Ti film 9 is nitridedthereby to form a surface-nitrided Ti film 9 b having a thickness ofabout 6 nm.

Subsequently, a W film 21 is formed all over the surface of thesubstrate so as to fill the contact hole with the W film 21. This W film21 can be formed by making use of a blanket CVD method employing a mixedgas comprising WF₆, SiH₄ and H₂ gas for instance (FIG. 29B). Then, the Wfilm 21 and the surface-nitrided Ti film 9 b abraded by making use ofthe CMP method until the surface of the interlayer insulating film 3 isexposed. As a result, a W plug comprising the W film 21 is formed in thecontact hole (FIG. 29C).

Then, a wiring layer is formed in the interlayer insulating film 3 bymaking use of a photolithography and the RIE method employing CHF₃ gas(FIG. 29D). This wiring groove is formed in a region including theaforementioned contact hole.

Since CHF₃ gas is employed in this step, the selectivity ratio among theW film (W plug) 21, the surface-nitrided Ti film 9 b and the interlayerinsulating film (SiO₂) 3 can be made higher. As a result, thesurface-nitrided Ti film 9 b can be left remained around the W plug 21,and the etch-back of the plug can be limited within 10 nm.

Then, another Si film 7 is deposited all over the substrate by means ofLP-CVD method so as to fill the interior of the wiring groove with theSi film 7. Thereafter, any superfluous portion of the Si film 7 which isdisposed outside of the wiring groove is selectively removed by makinguse of the CDE method or CMP method (FIG. 29E).

After a native oxide film formed on the upper surface of the Si film 7is removed by means of Ar sputter-etching, an Al film and a Ti film 9are successively formed by means of a sputtering method all over thesurface without breaking vacuum (FIG. 29F).

Thereafter, the substrate is heat-treated for 60 minutes in a furnaceheated to a temperature of 450° C., whereby allowing the Si film 7 to besubstituted by the Al film 8, and at the same time the Si film 7 isallowed to react with the Ti film 9 to form a Ti silicide compound,thereby allowing the Si film 7 to be absorbed by the Ti film 9. Duringthis step, a Ti/Ti silicide film 10 is formed (FIG. 29G).

Then, the Ti/Ti silicide film 10 and any superfluous portion of the Alfilm are removed (abraded) by means of CMP method. As a result, an Alwiring layer (a second wiring layer) comprising the Al film is formed inthe interior of the wiring groove.

In this case, a soft abrasive cloth can be employed to abrade the Alfilm (a first wiring layer) 8, thereby lowering the surface level of theAl film 8 from the surface level of the interlayer insulating film 3 bya thickness of about 20 nm (FIG. 29H).

After a native oxide film formed on the upper surfaces of the Al film 8and W plug 21 is removed by means of Ar sputter-etching, a TiN film 14having a thickness of 30 nm is formed all over the surface withoutbreaking vacuum (FIG. 29I).

Finally, the Ti/Ti silicide film 10 disposed outside of the wiringgroove is removed by means of CMP method (FIG. 29J).

Since the W plug 21 is directly contacted with the TiN film 14 accordingto this example, the problem of disconnection of wiring can be hardlyraised even if the migration of Al in the Al wiring layer 8 occursduring the operation of device, thereby ensuring a high reliability ofdevice.

EXAMPLE 28

There is a problem in the process wherein a substitutive film such as anSi film which has been formed in the interior of a contact hole or awiring groove is substituted by a conductive film such as an Al filmwhich has been formed on the substitutive film, and the substitutivefilm thus substituted is then allowed to react with an absorption filmsuch as a Ti film thereby to be absorbed by the absorption film.Specifically, according to this process, a reaction product film to beformed through a reaction between the substitutive film and theabsorption film, a superfluous absorption film which is left unused forthe reaction, and a superfluous conductive film disposed outside of thewiring groove are caused to remain in the form of a laminate film at theupper portions of the contact hole and wiring groove.

This kind of laminate film is relatively high in resistance as comparedwith the single layer of a conductive film so that if it is leftremained as mentioned above, the wiring cannot be employed as a wiringfor an LSI. Therefore, it is imperative to remove any superfluousmaterials, in particular the reaction product layer, thereby leaving theconductive film only in the interior of the wiring groove.

By the way, in a damascene type (or a dual damascene type) wiringstructure as proposed by this invention, it is possible to remove anysuperfluous portion by means of the CMP method.

However, in the case of the aforementioned laminate film comprising aplurality of films each differing from one another in quality, atreatment by means of a multi-stage CMP method is required to beperformed, i.e. the abrasive or abrasive cloth is required to befrequently exchanged so as to meet with the quality of each film to beabraded, thus making the process troublesome.

Further, depending on the layout of pattern of wiring, the quantity ofthe substitutive film increases locally, thus resulting in thenon-uniformity of the thickness of the absorption film remaining as asuperfluous material, of the thickness of reaction product, or of thethickness of superfluous portion of the conductive film. Therefore, itis very difficult to perform an uniform abrasion in plane ofsemiconductor chip or of the wafer.

Even in such a case, it is possible, by removing the upper layer portionby means of a wet etching method or the CDE method, to finish theabrasion with a single CMP process. Specific example of this method willbe explained below, wherein an Si film, an Al film and a Ti film areemployed as a substitutive film, a conductive film and an absorptionfilm, respectively.

When an Si film, an Al film and a Ti film are employed, a laminate filmconsisting of a Ti film/a Ti silicide film/an Al film is already formedon the upper portion of substrate at the moment when the substitutionreaction between the Si film and the Al film has been finished.

If a heated hydrogen peroxide aqueous solution is employed as an etchingsolution in this case, the Ti film can be selectively removed. If thelaminate film is treated in this manner, the remaining silicide film/Alfilm can be removed by the CMP employing a common abrasive for thesilicide film/Al film, e.g. colloidal silica-based abrasive, i.e. by asingle process of the CMP.

There is a problem when the density of Si is relatively high at a lowerregion that an Si nodule tends to be generated at this region and isturned into particles in the CMP process, thus generating a scratch.

This problem can be solved by removing the Si nodule by means of the CDEmethod at the moment when the surface of the Si nodule is exposed afteran wet etching or during the process of CMP.

Furthermore, when an Si film, an Al film and a W film are employed as asubstitutive film, a conductive film and an absorption film,respectively, a laminate film consisting of a W film/a W silicidefilm/an Al film is already formed on the upper portion of substrate atthe moment when the substitution reaction between the Si film and the Alfilm has been finished.

If a heated hydrogen peroxide aqueous solution is employed as an etchingsolution in this case, the W film can be selectively removed. On theother hand, the W silicide film can be selectively removed by the CDEmethod employing CF₄. If the laminate film is treated in this manner,the remaining Al film can be removed by a single process of the CMP.

EXAMPLE 29

First of all, a first wiring layer consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating filmis formed all over the upper surface of the substrate. Then, a contacthole and a wiring groove are successively formed in the interlayerinsulating film.

Then, a native oxide film formed on the upper surface of the firstwiring layer which has been exposed on the bottom of the contact hole isremoved by means of a surface treatment. Then, an amorphous Si film (aboron doped amorphous Si film) is deposited all over the substrate bymeans of LP-CVD method so as to prevent any void from generating in theinterior of the contact hole.

A specific method of forming this boron doped amorphous Si film is asfollows. Namely, the temperature of substrate is set to 350° C. and,after the temperature of substrate is stabilized, disilane gas anddiborane gas (flow rate: 50 (disilane gas):1 (diborane gas)) isintroduced into a chamber, in-which the boron doped amorphous Si film isallowed to deposit under a pressure of 0.1 torr.

It is also possible to deposit other kinds of Si film, such as apolycrystalline Si film, an amorphous Si film or a boron doped amorphousSi film in place of the aforementioned boron doped amorphous Si film.However, a deposition temperature of at least 600° C. in the case of thepolycrystalline Si film, and at least 420° C. in the case of theamorphous Si film would be required for achieving a practicallysufficient deposition rate of Si film.

On the other hand, in the case where the constituent material of thefirst wiring layer contains a low melting point metal, if the substrateis heated after a contact hole is formed in the interlayer insulatingfilm while allowing the first wiring layer formed on the bottom ofcontact hole to be exposed, the low melting point metal would be causedto swell in the contact hole due to a stress from the insulating filmexisting near the wiring layer. As a result, a void may be generated inthe wiring portion, thus badly affecting the reliability of the wiring.

The swelling of this low melting point metal in a contact hole is knownto occur when it is heat-treated at a temperature of more than 400° C.Therefore, the Si film is required to be formed at a temperature of 400°C. or less.

If the first wiring layer is consisted of a low melting point metal asmentioned above, the employment of a polycrystalline Si film or anamorphous Si film as a substitutive film may not be suited because of ahigh temperature required for the deposition of these films.

By contrast, in the case of the boron doped amorphous Si film (borondoped a-Si film), even if the deposition temperature is 400° C. or less,a sufficient deposition rate can be achieved as shown in FIG. 30, sothat the film-forming process of the Si film to be employed as asubstitutive film can be performed at a relatively low temperature andwithin a shorter period of time.

Moreover, the lower the temperature is, the more it becomes possible toproceed the deposition of film on a substrate within a reactionrate-determining region of disilane and diborane, thus making itpossible to obtain a more conformal and void-free Si film.

If the substitution reaction between the Si film and the Al film ispermitted to proceed by using an Si film (a substitutive film)containing a void, the void may be kept remained in the Al film to beobtained after the substitution. Therefore, the formation of a conformalSi film is desirable.

Since a boron doped amorphous Si film is employed as a substitution filmin this example, it is possible to deposit a conformal Si film which canbe deposited at a lower temperature and within a shorter period of time.

Then, the boron doped amorphous Si film is selectively removed by meansof the CMP method or CDE method so as to leave the boron doped amorphousSi film only in the interiors of the contact hole and the wiring groove,thus removing any superfluous portion of the boron doped amorphous Sifilm.

Then, the native oxide film or impurities such as F and C which areformed on the surface of the boron doped amorphous Si film are removedby means of reverse sputtering, and then an Al film and a Ti film aresuccessively deposited all over the upper surface of the resultantsubstrate without breaking vacuum.

Thereafter, the substrate is heat-treated for 90 minutes at atemperature of 450° C., whereby allowing the boron doped amorphous Sifilm to be substituted by the Al film, and at the same time allowing theboron doped amorphous Si film to be reacted with the Ti to form a Tisilicide compound and a Ti boride, thereby allowing the boron dopedamorphous Si film to be absorbed by the Ti film, thus obtaining acontact hole and a wiring groove, both being filled with the Al film.During this step, a mixed layer comprising a Ti/Ti silicide film, a Tisilicide film and a Ti boride film is formed.

Finally, the mixed layer comprising a Ti/Ti silicide film, a Ti silicidefilm and a Ti boride film. and any superfluous portion of the Al filmand Al/Ti mixed film are all removed by means of the CMP method. As aresult, an Al plug and an Al wiring layer (a second wiring layer) bothconsisting of the Al film are formed in the interiors of the contacthole and the wiring groove, respectively.

Meanwhile, for the purpose of comparison with the device of thisexample, an Al film is selectively left remained in the interiors of thecontact hole and the wiring groove by using a substrate bearing the samepattern density and by repeating the same procedures as mentioned aboveexcept that a polycrystalline Si film or an amorphous Si film isemployed as a substitutive film and filled in the interiors of thecontact hole and the wiring groove.

As a result, the specific resistance was 3.7 μΩcm in the case where thesubstitution was performed using the polycrystalline Si film, and 3.5μΩcm in the case where the substitution was performed using theamorphous Si film.

By contrast, the specific resistance was 3.3 μΩcm in the case where thesubstitution was performed using the boron doped amorphous Si filmaccording to this example, thus indicating a lower value as comparedwith aforementioned different kinds of Si film. Moreover, this lowspecific resistance is very close to the specific resistance of an alloywherein Si is incorporated into an Al film to an extent of solidsolution limit.

The factors for causing a difference in specific resistance of the Alfilm filled in the contact hole and wiring groove depending on the kindsof the Si film. (substitutive film) are illustrated in FIG. 31.

Namely, FIG. 31 shows the dependency of the specific resistance of theAl film on the time required for the substitution treatment wherein aboron doped amorphous Si film and a polycrystalline Si film arerespectively subjected to the substitution treatment at a temperature of450° C., thereby filling the contact hole and wiring groove with the Alfilm in the same procedures as described above.

It will be seen from FIG. 31 that irrespective to the kinds of Si filmto be functioned as the substitutive film, there is a heat treatmenttime, in relative to the heat treatment temperature, that gives aminimum value in specific resistance of the charged Al film.

The heat treatment in this example using a boron doped amorphous Si filmas a substitutive film is based on this result, i.e. a heat treatmenttime of 90 minutes which gives a minimum value in specific resistance ata temperature of 450° C. is adopted.

In the case where the polycrystalline Si film was employed as asubstitutive film, the minimum value of specific resistance was obtainedwhen the heat treatment was performed for about 150 minutes at atemperature of 450° C. The specific resistance of the Al film ultimatelyobtained in this case was lowered to nearly 3.3 μΩcm.

In the case where the amorphous Si film was employed as a substitutivefilm, the minimum value of specific resistance of the Al film filled inthe contact hole and wiring groove that was obtained when the heattreatment was performed at a temperature of 450° C. was located at anintermediate region of time between where the boron doped amorphous Sifilm was employed and where the polycrystalline Si film was employed.

By suitably combining the substitution heat treatment temperature andthe heat treatment time in each kind of Si film so as to achieve aminimum value in specific resistance of the Al film filled ultimately,an Al film of low resistance can be obtained.

In particular, if an amorphous Si film is selected rather than apolycrystalline Si film, furthermore if a boron doped amorphous Si filmis selected from among these Si films as an Si film to be initiallyfilled in a contact hole or in a wiring groove, the time required forthe substitution heat treatment can be shortened.

Next, the advantage of employing a boron doped amorphous Si film as asubstitutive film will be explained with reference to FIG. 32. FIG. 32shows a graph wherein the factors for constituting the specificresistance shown in FIG. 31 are separately illustrated.

In the substitution heat treatment, the Si film is caused to be drawnout of a contact hole or a wiring groove through the silicidation of theTi film formed on the Al film, and at the same time, substituted by theAl film. During this substitution process, the diffusion of Ti into theAl film takes place also, in addition to the mutual diffusion betweenthe Si film and the Al film, and the silicidation of Ti.

Since the absorption of Si proceeds more prominently on the side of theSi film which faces the absorption film in the initial stage ofsubstitution reaction, so that the quantity of the Si and Si nodule inthe Al film is reduced, thus lowering the specific resistance of the Alfilm filled in the contact hole or wiring groove.

The time required for the reduction of resistance of the Al film thatcan be attained by the reduction of the quantity of Si is determinedaccording to the density wiring pattern which has been formed in theunderlying layer as well as according to the filling ratio of the Sifilm in the contact hole or wiring groove.

However, if the heat treatment time is prolonged, due to the diffusionof Ti into the Al film, the diffusion of Ti into the Al film is furtherpromoted, thus leading to an increase in resistive component in the Alfilm. As a result, the aforementioned minimum value in relative to thesubstitution heat treatment temperature is cause to be formed in thespecific resistance of the Al film to be ultimately filled in thecontact hole or the wiring groove.

However, if a boron doped amorphous Si film is employed as thesubstitutive film, the mutual diffusion between Al and Si is promoted(activated) and at the same time, the movement of B and Si toward the Tifilm side is also accelerated, thus making it possible to shorten thesubstitution reaction between the Al film and the Si film.

Due to this shortening of heat treatment time, the diffusion time of Tiinto the Al film can be minimized, and hence the minimum value inspecific resistance of the resultant Al film that can be achieved froman appropriate combination of temperature and time in the substitutionheat treatment can be obtained in a shorter time as compared with whereother kinds of Si film are employed. As a result, an Al film which islower in specific resistance can be filled in the contact hole or in thewiring groove.

Moreover, since this boron doped amorphous Si film, which can bedeposited at relatively low temperature, can contain a larger amount ofhydrogen as compared with other kinds of Si film, it is expected thatthe mutual diffusion between Al and the boron doped amorphous Si film isfurther activated.

Furthermore, when the substitution reaction of Al film is performed withan employing of this boron doped amorphous Si film, the boron which hasbeen diffused into the Ti film side forms a Ti boride at or near theinterface between the Al film and the Ti film, thus inhibiting the Tifrom diffusing into the Al film.

Due to these effects, it is possible with the employment of this borondoped amorphous Si film to more effectively alleviate an increase inresistance (due to the diffusion of Ti into the Al film filled in thecontact hole or wiring groove) as compared with other kinds of Si film,or even if the heat treatment time is prolonged, as shown in FIG. 31.

These effects can be more effectively utilized if this boron dopedamorphous Si film (to be formed as a substitutive film) is deposited soas to form a gradient in concentration of boron, i.e. the concentrationof boron increases gradually or step-wise toward the Al film.

When a high concentration region of boron is existed at the upper layer,the reaction of forming a Ti boride is allowed to take place faster thanthe Ti-silicifying reaction during the substitution heat treatmentbetween the Al film and the boron doped amorphous Si film, so that thediffusion of Ti into the Al film can be inhibited from the early stageof the heat treatment.

When the Ti boride film (which is capable of inhibiting the mutualdiffusion between Al and Ti due to the diffusion of Ti, or inhibitingthe reaction of them) is interposed in this manner, the formation ofAl/Ti compound can be inhibited in the Al film or at the Al/Tiinterface. As a result, the gradient of stress to the Al film due to thevoluminal expansion resulting from the formation of the Al/Ti compoundcan be alleviated, thus making it possible to prevent the generation ofvoid in the Al wiring.

In the explanation of this example, a Ti boride layer is formed as adiffusion-inhibiting layer. However, almost the same effect can beobtained even if a Ti silicide layer 24 a is formed as adiffusion-inhibiting layer (FIG. 35). It is also possible to obtainalmost the same effect by the application of other kinds of film whichis capable of effectively inhibiting the mutual reaction between Al andTi, i.e. by the formation of a thin W film 24 b at the Al/Ti interface,which is incapable of forming a compound with Al at the substitutionheat treatment temperature but is capable of allowing Al and Si to passtherethrough (FIG. 36A); or by the formation of a TiSi compound layer 25through a substitution reaction between Si and Al (FIG. 36B).

The W film in this case can be formed by means of sputtering or bymaking use of a CVD method.

EXAMPLE 30

First of all, a wiring groove 5 and a contact hole 4 both being filledwith an Si film 7 are formed (FIG. 33A). After a Ti film 9 is formed allover the surface of the substrate, an Al film 8 is formed (FIG. 33B).When these films are subjected to heat treatment as they are, a TiSicompound is formed at the Ti/Si interface, and an AlTi compound isformed at the Al/Ti interface. Since any of AlTi compound layer/Tilayer/TiSi layer is incapable of functioning as a diffusion barrieragainst Al, Al is allowed to pass through these AlTi compound layer/Tilayer/TiSi layer, thereby making it available for the substitution withSi (FIG. 33C).

Then, the Al film and the AlTi compound layer/Ti layer/TiSi compoundlayer 10 are removed by means of the CMP (FIG. 33D). At this moment, theTiSi compound layer 23 is formed even in the inside of the wiring grooveduring the previous heat treatment, so that even when the CMP is carriedout down to the surface of interlayer insulating layer, the TiSicompound layer 23 is left remained in the wiring groove. This TiSicompound layer remained in this manner functions as a compensating leadwire for allowing an electric current to pass therethrough when a voidis generated in the Al wire, thus improving the reliability of wire. Ifthe wiring groove is deeply formed in advance, the thickness of the TiSicompound layer can be adjusted by additionally performing the CMP.

In the foregoing explanation, both wiring groove 5 and contact hole 4are filled with Al. However, Al may be filled only in the contact hole4. Namely, the contact hole is filled with the Al film 8 (FIG. 34A), theTi film 9 is deposited all over the surface of the substrate, and an Alfilm 8 is formed (FIG. 34B). When these films are subjected to heattreatment as they are, a TiSi compound is formed at the Ti/Si interface,and an AlTi compound is formed at the Al/Ti interface (reference numeral10). Since any of AlTi compound layer/Ti layer/TiSi layer is incapableof functioning as a diffusion barrier against Al, Al is allowed to passthrough these AlTi compound layer/Ti layer/TiSi layer, thereby making itavailable for the substitution with Si (FIG. 34C).

Then, the Al film and the AlTi compound layer/Ti layer/TiSi compoundlayer are removed by means of the CMP (FIG. 34D). At this moment, theTiSi compound layer is formed even in the inside of the wiring grooveduring the previous heat treatment, so that even when the CMP is carriedout down to the surface of interlayer insulating layer, the TiSicompound layer 23 is left remained in the wiring groove. If the wiringgroove is deeply formed in advance for the purpose of lowering the plug,the thickness of the TiSi compound layer can be adjusted by additionallyperforming the CMP.

After an Al plug is formed in advance as mentioned above, an interlayerinsulating film 3 is formed and selectively etched to a depth reachingto the Al plug, thus forming a wiring groove, into which a lowresistance metal such as Cu is filled, thereby making it possible toobtain a wiring of low resistance.

EXAMPLE 31

This example explains a method of heat treatment for more positivelyforming the diffusion-inhibiting layer which has been explained inExample 29.

First of all, a first wiring layer consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating filmis formed all over the upper surface of the substrate.

Then, the interlayer insulating film is selectively etched by making useof photolithography and RIE to a depth reaching to the first wiringlayer, thus forming a contact hole, and at the same time a wiring grooveis selectively formed likewise at a region including this contact hole.Namely, the contact hole connected with the first wiring layer and thewiring groove are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer which has been exposed on the bottom of the contact hole isremoved by means of a surface treatment. Then, an Si film is depositedall over the substrate by means of CVD method so as to fill theinteriors of the contact hole and the wiring groove with the Si film.Then, any superfluous portion of the Si film is selectively removed bymeans of the CMP method or CDE method so as to leave the Si film in theinterior of the contact hole.

Then, the native oxide film formed on the surface of the Si film isremoved, and then an Al film and a Ti film are successively depositedall over the upper surface of the resultant substrate without breakingvacuum.

Then, as shown in FIG. 37, a heat treatment is performed for 3 hours ata temperature of not more than 400° C. thereby preferentially forming aTiSi compound to be functioned as a diffusion-inhibiting layer againstTi and Al. As a result, a TiSi compound film is formed at the interfaceof Al/Ti, this TiSi compound film being functioning as an inhibitinglayer for inhibiting the interdiffusion of Ti/Al, thus inhibiting theformation of an Al/Ti compound in the Al film and at the interface ofAl/Ti. After this diffusion-inhibiting layer is formed, a hightemperature heat treatment is performed for one hour at a temperature of400° C. or more so as to allow a Ti silicide-forming reaction to takeplace, thereby promoting the absorption of Si by the Ti and at the sametime accomplishing the substitution reaction between Al and Si. It ispossible with this method to inhibit the formation of the AlTi compound,to inhibit an excessive voluminal expansion of the upper Al film, and toalleviate the stress to Al. At the same time, it is possible tosufficiently shorten the substitution reaction between Si and Al.

EXAMPLE 32

First of all, a first wiring layer consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating filmis formed all over the upper surface of the substrate.

Then, a contact hole and a wiring groove are successively formed in theinterlayer insulating film. Then, a native oxide film formed on theupper surface of the first wiring layer which has been exposed on thebottom of the contact hole is removed. Then, an Si film is deposited allover the substrate in a manner to prevent any void from generating inthe interior of the contact hole.

Then, any superfluous portion of the Si film is selectively removed bymeans of the CMP method or CDE method so as to leave the Si film in theinteriors of the contact hole and wiring groove.

Then, the native oxide film or impurities such as F and C which areformed on the surface of the boron doped amorphous Si film are removedby means of reverse sputtering, and then an Al film and a Ti film aresuccessively deposited all over the upper surface of the resultantsubstrate without breaking vacuum.

Thereafter, the substrate is heat-treated for 300 minutes at atemperature of 450° C., whereby allowing the Si film to be substitutedby the Al film, and at the same time allowing the Si film to be reactedwith the Ti to form a Ti silicide compound, thereby allowing the Si filmto be absorbed by the Ti film, thus obtaining a contact hole and awiring groove, both being filled with the Al film. During this step, aTi/Ti silicide film is formed.

As mentioned in Example 25, during the substitution heat treatmentbetween the Si film and the Al film, not only the silicidation reactionto absorb the Si film by the Ti film but also the diffusion of Ti intothe Al film is taken place. This diffusion of Ti becomes a cause forincreasing the resistance of the Al film when a heat treatment of longtime is required.

Then, the Ti/Ti silicide and any superfluous portion of the Al film areremoved by means of the CMP method so as to leave the Al film in theinteriors of the contact hole and wiring groove.

Then, through a heat treatment in an N₂ gas atmosphere, the Ti which hasbeen diffused into the Al film is allowed to be diffused out of the Alfilm filled in the contact hole and wiring groove, thereby dischargingTi from the Al film.

Finally, the surface of the Al film on which the precipitated Ti and Tinitrides are formed is treated again by means of the CMP method, wherebyremoving these Ti and Ti nitrides. As a result, a connector plugcomprising the Al film filled in the interior of contact hole and awiring comprising the Al film filled in the interior of the wiringgroove can be obtained.

Since the Ti which has been diffused into the Al film during thesubstitution treatment can be discharged out of the Al film by a heattreatment in an N₂ gas atmosphere, the specific resistance of the Alfilm can be effectively lowered.

The step of discharging Ti out of the Al film by a heat treatment in anN₂ gas atmosphere can be performed by employing an N₂ gas atmosphere inthe step of the substitution heat treatment. Alternatively, the step ofdischarging Ti out of the Al film by a heat treatment in an N₂ gasatmosphere can be performed after the substitution heat treatment butprior to the step of removing the Ti/Ti silicide and any superfluousportion of the Al film.

The gas atmosphere is not confined to the N₂ gas atmosphere, but may bea gas atmosphere containing N, B, H, C or a combination of theseelements, such as NH₃, B₂H₆ or CO₂. Namely, any kinds of gas can beemployed as far as the gas atmosphere does not badly affect the processinvolved and allows the Ti to be discharged out of the Al film.

Further, the discharging step of Ti can be performed as follows. Namely,after filling the contact hole and wiring groove with an Al film, andthe upper Ti/Ti silicide and superfluous portion of Al film are removed,the substrate is subjected to additional heat treatment at a temperaturewhich is higher than the solid solution limit of Ti diffused in the Alfilm but is lower than the substitution heat treatment temperature ofthe Al film and Si film, and then the substrate is allowed to coolgradually, thereby allowing Ti to discharge until solid solution limitof Ti in the Al film at a lower temperature is reached. Further, whenthis temperature sequence for discharging Ti is performed in an N₂ gasatmosphere or the aforementioned various kinds of gas atmosphere, thedischarge of Ti from the Al film can be more effectively carried out.

It may be preferable, at the occasion of forming the Al film on thesurface of the Si film, to form a sufficiently thick Al film in relativeto the diffusion of Ti into the Al film in the substitution heattreatment. If the Al film is formed in this manner, a high resistanceportion where the diffuse Ti remains and disposed higher than the wiringgroove can be removed at the occasion of removing the Ti/Ti silicide anda superfluous portion of Al film after the substitution heat treatment,so that even if the substrate is heated at the same temperature and thesame time, the interiors of contact hole and wiring groove can be filledwith an Al film which is relatively free from a high resistance portiondue to the diffusion of Ti.

Namely, if the temperature and time for the substitution heat treatmentare determined according to the substitution between the Si film and theAl film, and if the quantity of Ti to be diffused under thesetemperature and time is adjusted by the film thickness of the Al film,an Al wiring and an Al plug which are low in resistance can be obtained.

It is of course possible to combine various methods illustrated in theseexamples as a method of reducing an increase of resistance originatingfrom Ti being diffused and remaining in the Al film. For example, when awiring pattern is consisted of various pattern densities, the time forthe substitution heat treatment may be required to be prolonged inconformity with the region where the quantity of Si is highest even ifthe substitution is already finished and an increase in resistance isinitiated due to the diffusion of Ti into the Al film at other regionwhere the quantity of Si is relatively small. Even in such a situation,it is possible through the combination of these methods to form an Alfilm of ultimately low resistance.

EXAMPLE 33

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole 4, and at the same time a wiringgroove 5 is selectively formed likewise at a region including thiscontact hole 4. Namely, the contact hole 4 connected with the firstwiring layer 1 and the wiring groove 5 are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer 1 which has been exposed on the bottom of the contact hole4 is removed by means of a surface treatment. Then, an Si film 7 isdeposited all over the substrate by means of CVD method so as to fillthe interiors of the contact hole 4 and the wiring groove 5 with the Sifilm 7. Then, any superfluous portion of the Si film 7 is selectivelyremoved by means of the CMP method or CDE method so as to leave the Sifilm 7 in the interior of the contact hole 4.

Then, the native oxide film formed on the surface of the Si film 7 isremoved, and then an Al film 8 and a Ti film 9 are successivelydeposited all over the upper surface of the resultant substrate withoutbreaking vacuum. Then, an SiO₂ film 26 and a Ti film 9 are formedthereon (FIG. 38A).

Then, a heat treatment is performed for two hours at a temperature of450° C., during which the substitution between the Si film and the Alfilm is effected, and the silicidation reaction is allowed to take placebetween the Si film and the Ti film, thereby forming a Ti silicide andallowing the Si film to be absorbed by the Ti film.

In substitution reaction, due to the formation of the Ti silicide, thevolume of the upper portion thereof is caused to expand as compared withthe initial Ti volume, thus imposing a tensile stress (in-planedirection) on the Al film. If the volume of the Ti film is large, thequantity of AlTi compound to be formed at the Al/Ti interface would beincreased, thus making the voluminal expansion of the compound filmbecomes more prominent. If the tensile stress due to this voluminalexpansion of the compound film becomes excessive, the stress gradient iscause to generate, and hence a void is caused to be generated toalleviate this stress gradient, thus possibly generating a void in theAl wiring.

In this example, there is preliminarily provided on the surface of theTi film with a film (SiO₂ film 26 ) which is capable of giving a stressin the direction of compression in conformity with the voluminalexpansion, due to the formation of Ti compound, of the film formed onthe Al film. It is possible with this film (SiO₂ film 26) to suppressthe expansion in planar direction of the Ti compound film and at thesame time to inhibit the generation of void in the Al wiring.

In the foregoing explanation of this example, an SiO₂ film is employedas a film which is capable of giving a stress in the direction ofcompression. However, it is also possible to employ a W film or an SiNfilm. This kind of film may be disposed inside of the Al film as far asit is capable of allowing Al and Si to pass therethrough. For example,when a thin W film is formed inside of the Al film, Al and Si would passthrough the grain boundaries of W, thereby allowing the substitutionreaction to take place between Al and Si. At the same time, theabsorption of Si by the Ti film would proceed. Accordingly, the W in theAl film would not obstruct the substitution reaction between Al and Si,but act to alleviate the stress on the Al film filled in the wiringgroove or contact hole.

EXAMPLE 34

First of all, a first wiring layer 1 consisting of Al is formed on an Sisubstrate provided with an element. Then, an interlayer insulating film3 is formed all over the upper surface of the substrate.

Then, the interlayer insulating film 3 is selectively etched by makinguse of photolithography and RIE to a depth reaching to the first wiringlayer 1, thus forming a contact hole 4, and at the same time a wiringgroove 5 is selectively formed likewise at a region including thiscontact hole 4. Namely, the contact hole 4 connected with the firstwiring layer 1 and the wiring groove 5 are successively formed.

Then, a native oxide film formed on the upper surface of the firstwiring layer 1 which has been exposed on the bottom of the contact hole4 is removed by means of a surface treatment. Then, an Si film 7 isdeposited all over the substrate by means of CVD method so as to fillthe interiors of the contact hole 4 and the wiring groove 5 with the Sifilm 7. Then, any superfluous portion of the Si film 7 is selectivelyremoved by means of the CMP method or CDE method so as to leave the Sifilm 7 in the interior of the contact hole 4.

Then, after the native oxide film formed on the surface of the Si film 7is removed, an Al film 8 is deposited all over the upper surface of theresultant substrate. Thereafter, the substrate is transferred withoutbreaking vacuum to a chamber provided with a Ti target. Then, thesputtering of the Ti target is performed in a gaseous atmospherecomprising hydrogen and Ar which are mixed in a suitable ratio, thusforming on the Al film 8 a film 9 containing Ti or a TiHx compoundimpregnated with a sufficient amount of hydrogen (FIG. 39A). This film 9is formed under the condition which enables to obtain a film having alarger volume as compared with the ordinary Ti film that can be obtainedthrough sputtering employing an Ar gas.

Thereafter, the substrate is heat-treated for two hours at a temperatureof 450° C. in a furnace evacuated to a high vacuum level, wherebyallowing the Si film to be substituted by the Al film, and at the sametime allowing the Si film to reach the Ti or TiHx film impregnated withhydrogen thereby to form a Ti silicide. The hydrogen held in the Ti filmis caused to be dispersed out of the Ti film during the heat treatment.While, the hydrogen held in the TiHx film is thermally decomposed at450° C. or decomposed through a silicifying reaction and then dispersed.When hydrogen is dissociated in this manner, the volume of theabsorption film is caused to shrink from the initial volume (FIG. 39B).

The dissociation/outward dispersion reaction of hydrogen does not causea large change in volume of a silicide as compared with the case wherethe ordinary Ti film is turned into a silicide or into an AlTi compoundthrough a silicidation reaction. Therefore, the stress to be imposed onthe Al film due to an excessive voluminal change (due to the formationof a TiSi compound or an AlTi compound) of the film formed on the Alfilm can be alleviated, and at the same time the generation of void inthe Al film can be inhibited, thus making it possible to obtain an Alwiring or an Al plug which are excellent in reliability (FIG. 39C).

EXAMPLE 35

FIGS. 40A to 40E show respectively a cross-sectional view illustratingin stepwise the method of forming an Al plug according to this example.

First of all, a first wiring layer 102 is formed on a substrate providedwith an element. Then, an interlayer insulating film 103 is formed allover the upper surface of the substrate.

Then, the interlayer insulating film 103 is selectively etched to form acontact hole 104 and a wiring groove 105 (FIG. 40A).

Then, an alloy film 106 consisting of a eutectic alloy (Al—Snx; x=about86 at %) of Al and Si is formed by means of sputtering. The sputteringcan be performed by making use of a eutectic alloy target consisting ofAl and Sn the mixing thereof being adjusted to form a desired eutecticalloy film, or a mosaic-like target consisting of Al and Sn. In thiscase, an Al—Sn alloy is formed in advance in the contact hole and wiringgroove by means of a sputtering method which is excellent inrectilinearity (i.e. in the direction perpendicular to the surface ofsubstrate), for example, a long throw sputtering method whereinsubstrate is distanced apart from a target (TS distance).

It is possible in this case to heat the substrate up to a temperature toturn the Al—Sn film into a liquid phase, thereby uniformly filling thecontact hole and wiring groove with the Al—Sn film. The thickness of theAl—Sn film should sufficient enough to enable the Al in the Al—Sn filmto be sufficiently filled in the contact hole and wiring groove (FIG.40B).

Then, the substrate is heated to a temperature of 420° C. or more (inthe case of this alloy composition) but lower than a desired processtemperature to obtain a liquid phase of the Al—Sn alloy. The term, “adesired process temperature” herein means a temperature which does notexceed over the highest temperature to be employed in the formation of amulti-layer wiring as well as in the sintering of an Al wiring.

After the Al—Sn film deposited in advance is turned into a liquid phase106 a and kept stand for a while to make it equilibrated, the liquidphase is cooled down to sufficiently lower than 420° C. (a temperaturewhich enable to obtain a liquid phase according the equilibrium phasediagram of the composition where Sn content is 86 at %), i.e. 350° C. Asa result, since the liquid phase of Al—Snx alloy (x=about 86 at %) iscooled down to 350° C. (where an equilibrium of the Al—Snx alloy isx=about 92.3 at %), an excessive portion of Al (about 8 at %) is allowedto precipitate on the insulating film including the contact hole and thewiring groove (FIG. 40C).

Namely, the contact hole and the wiring groove are filled with theeutectic Al film 106 b (FIG. 40D). This eutectic Al film is a filmmainly consisting of Al and containing Sn in an amount which correspondsto less than the maximum concentration wherein the Sn of liquid phasecan be equilibrated with the Al precipitated when the liquid phase ofthe Al—Sn film is formed in the contact hole and wiring groove. Thetemperature at the step of precipitating the Al may be a temperatureregion which enable the two-phase (solid phase/liquid phase) co-existingregion to be kept in an equilibrium condition. Therefore, in the case ofthe aforementioned Al—Sn alloy, the temperature is more than 228° C.which is a eutectic line in the equilibrium diagram and less than 420°C. which is a liquid phase line.

The step of precipitating Al can be performed not only by shifting theequilibrium concentration through cooling, but also by selectivelyreducing the concentration of Sn. The main point of the step ofprecipitating Al, which is to used as a conductive film, is to shift theequilibrium concentration, whereby allowing the conductive film to beprecipitated. A combination of Al and Sn is the one which enables aeutectic to be formed, so that these metals do not form a compound inthe equilibrium thereof, i.e. they are separated into two phases. Sn isa metal having a very low melting point as compared with Al and beingincapable of forming a compound with Al, and hence when Sn is made intoa eutectic together with Al, the melting point of the eutectic can bedecreased lower than the process temperature to be generally employed inthe manufacture of the LSI, thereby making it possible to easily obtaina liquid phase thereof.

By making use of a liquid phase excellent in fluidity, not only thefilling of a fine pattern or of a contact hole of high aspect ratio canbe facilitated, but also the process temperature for filling a contacthole or wiring groove can be lowered. In the foregoing explanation ofthis example, the interiors of the contact hole or wiring groove aredirectly filled with an Al—Sn film. However, a barrier film may beformed on the interiors of the contact hole or wiring groove in prior tofilling them with the Al—Sn film thereby to improve the wettability ofthe contact hole or wiring groove to the Al—Sn film, thus making itpossible to achieve an excellent step coverage of the Al—Sn film at theinitial stage of forming the film thereof.

When the barrier film is formed prior to forming the Al—Si film, it maybe formed in the concave portion, where Al is precipitated, as a barrieror precipitation seed. This barrier film can be easily formed by filmforming method such as anisotropic sputtering or the like.

Then, the Sn layer that has been segregated over. the surface ofsubstrate as well as the Al—Sn layer and Al layer which are leftremained outside of the contact hole and the wiring groove are removed.This removing step is performed by introducing a gas containing chlorine(Cl₂) into the chamber thereby allowing the gas to flow over the surfaceof the substrate, thereby removing the Sn layer and an excessive Al—Snlayer in the form of chlorides. Since Sn chloride is high in vaporpressure, i.e. higher than that of Al chloride, the Sn can beselectively removed with a suitable selective ratio in relative to Al bysuitably selecting the condition.

In this case, if the substrate is heated, the chlorides can be moreeffectively removed. The removal of the chlorides making use of gas flowcontaining Cl₂ can be performed with the RIE etch-back method or in theCDE etch-back method, thereby obtaining a higher effect. Furthermore,when an oxidizing gas is added to the gas flow in the etch-back processby means of the RIE or CDE, it is possible to improve the selectivitybetween Al and Sn, so that a plug or a wiring both consisting of anAl-precipitated film can be easily formed in a contact hole or in awiring groove, respectively. Although a gas containing chlorine isemployed for working a plug or a wiring in the foregoing explanation ofthis example, other kind of gas such as a gas containing Br, F or I maybe employed to obtain almost the same effects.

The Sn layer, the Al—Sn layer and the Al layer which are left remainedoutside of the contact hole and the wiring groove can be removed bymeans of a chemical mechanical polishing method (CMP) (FIG. 40E).

This example may be summarized by the following process flow.

(1) A step of forming an Al—Sn film in a recessed portion of pattern(contact hole or wiring groove);

(2) A step of forming a liquid phase of an Al—Sn film, or filling thecontact hole with a liquid phase;

(3) A step of precipitating Al on the interface or on the bottom ofcontact hole through a shifting of equilibrium concentration (A step ofprecipitating Al from a two-phase mixture region comprising the liquidphase and solid phase of an Al—Sn eutectic alloy);

(4) A step of forming a plug consisting mainly of Al through a growth ofan Al nucleus and layer with an Al precipitation nucleus formed in (3)being employed as a seed layer; and

(5) A step of working the wiring and plug for leaving a materialconsisting mainly of Al in the contact hole and wiring groove.

In the foregoing explanation, a long throw sputtering method which isone of the PVD methods excellent in rectilinearity of sputteringparticles is employed as a method for filling in advance an Al—Sn alloyin the contact hole and wiring groove. However, it is possible to employother method. For example, it is possible to employ an anisotropicsputtering method such as a collimation sputtering method wherein acollimator is interposed at an intermediate portion of TS distancewhereby to allow the sputtering particle components other than thecomponent exhibiting the perpendicular incidence to be adhered thereon;or a bias sputtering method employing an AC voltage or a high frequencyvoltage for applying it onto a substrate.

Furthermore, as far as it is possible to form an Al—Sn alloy film in thecontact hole or wiring groove, the ordinary sputtering method can beemployed. Moreover, the employment of ICB (Ion Cluster Beam) other thanthe sputtering is possible. The substrate may be heated in advance atthe occasion of depositing an Al—Sn alloy film up to the liquid phasetemperature of the alloy composition irrespective of the kinds of filmto be deposited in the contact hole or wiring groove, i.e. the film maybe an Al—Sn alloy film or a simple Sn film. Further, for the purpose ofsustaining the liquid phase of alloy at least in the contact hole orwiring groove, the liquid phase may be obtained by heating it underpressure.

EXAMPLE 36

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 41A to41E.

As shown in FIG. 41A, first of all, a first wiring layer 112 is formedon a substrate (not shown) provided with an element. Then, an interlayerinsulating film (SiO₂) 113 is formed over the first wiring layer 112.

Then, the interlayer insulating film 113 is selectively etched by makinguse of photolithography and RIE to form a contact hole (0.1 μm indiameter and 10 in aspect ratio) 114 and a wiring groove 115 (FIG. 41A).

Then, a Sn film is formed by means of sputtering. In this case, an Snfilm 116 is formed in advance in the contact hole and wiring groove bymeans of a sputtering method which is excellent in rectilinearity, forexample, a long throw sputtering method wherein substrate is distancedapart from a target (TS distance).

It is possible in this case to heat the substrate up to a temperature ofabout 232° C., thereby uniformly filling the contact hole and wiringgroove with the Sn film. Then, an Al film 117 is deposited all over thesubstrate by means of sputtering without breaking vacuum thereby to forma laminate film comprising Sn and Al (FIG. 41B).

Then, the substrate is heated to a temperature of 420° C. or more butlower than a desired process temperature. The term, “a desired processtemperature” herein means a temperature which does not exceed over thehighest temperature to be employed in the formation of a multi-layerwiring as well as in the sintering of an Al wiring.

As a result of this heat treatment, the Sn liquid phase 16 a depositedin advance and a liquid phase 117 a of Al film near the Sn/Al interfaceare obtained, and at the same time, the Al is allowed to diffuse intothe Sn liquid phase, whereby obtaining a liquid phase alloy of Al—Sn(FIG. 41C).

Then, the substrate is allowed to cool, and kept at a constanttemperature of about 300° C., during which an excessive portion of Al inrelative to the equilibrium concentration at this constant temperatureis allowed to precipitate over the insulating film. The resultantprecipitated Al nucleus 116 b is then utilized as a seed layer for theliquid phase growth of Al, the Al thus precipitated being filled in thecontact hole and the wiring groove (FIG. 41D). The process temperaturefor precipitating the Al in this case is a temperature region whichenable the two-phase (solid phase/liquid phase) co-existing region to bekept in an equilibrium condition, so that the temperature is more than228° C. which is a eutectic line in the equilibrium diagram.

Then, the Sn layer thus segregated as well as the Al—Sn layer 117 b andAl layer 116 b which are left remained outside of the contact hole andthe wiring groove are removed. This removing step is performed byintroducing a gas containing chlorine, thereby allowing the gas to flowover the surface of the substrate (if desired, by concurrently heatingthe substrate), thereby removing these layers in the form of chlorides.The removal of the chlorides making use of gas flow containing Cl₂ canbe performed with the RIE etch-back method or in the CDE etch-backmethod, thereby obtaining a higher effect.

It is also possible to remove the Sn layer, the Al—Sn layer and Al layerwhich are left remained outside of the contact hole and the wiringgroove by means of the CMP. As a result, the plug and wiring 116 b, bothformed of the precipitated Al film, can be formed in the contact holeand wiring groove, respectively (FIG. 41E).

During the formation of the connector plug or groove wiring in thisexample, the diffusion of Al into the liquid phase Sn film whichcorresponds in quantity to that can be existed in the two-phase (solidphase/liquid phase) co-existing eutectic region is taken place.Accordingly, when the Al—Sn liquid phase alloy formed through thisdiffusion is cooled and kept at a constant temperature, the superfluousportion of Al which has been exuded from the equilibrium composition isallowed to precipitate in the liquid phase alloy. By allowing Al to beprecipitated from the surface of the insulating film or from the contacthole, the formation of the plug can be achieved.

When the substrate is to be moved after finishing the step of formingthe Sn film and Al film to the step of heat treatment for melting thesefilms, this heat treatment can be performed by transferring it to avacuum chamber or in the same chamber where the formation of the Sn filmand Al film has been performed.

A film rich in Sn component in the Sn—Al film may be employed in placeof the Sn film to be employed at the beginning. Other kinds of filmwhich can be turned into a liquid phase at a suitable processtemperature can be also employed.

EXAMPLE 37

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 42A to42E.

As shown in FIG. 42A, first of all, a first wiring layer 122 is formedon a substrate (not shown) provided with an element. Then, an interlayerinsulating film 123 is formed over the first wiring layer 122.

Then, the interlayer insulating film 123 is selectively etched to form acontact hole (0.1 μm in diameter and 10 in aspect ratio) 124 and awiring groove 125 (FIG. 42A).

Then, a Sn film is formed all over the substrate by means of sputtering.In this case, an Sn film 126 is formed in advance in the contact hole124 and wiring groove 125 by means of a sputtering method which isexcellent in rectilinearity (FIG. 42B). It is possible in this case toheat the substrate so as to uniformly fill the contact hole 124 andwiring groove 125 with the Sn film.

Then, the substrate is transferred to a separate chamber for performinga heat treatment and a film formation through sputtering withoutbreaking vacuum. The film formation may be performed by any other methodother than sputtering. Then, the substrate is heated to a temperature ofabout 300° C. and then kept at this temperature thereby turning the Snfilm deposited in advance into a liquid phase. Under this condition, Alis fed through sputtering (FIG. 42C). As a result, an excessive portionof Al which is excluded from the equilibrium composition in thetwo-phase (liquid/solid phase) co-existing region of Al—Sn at 300° C. iscaused to diffuse into the Sn film.

As a result, an excessive portion of Al in. relative to the equilibriumconcentration at this constant temperature is allowed to precipitateover the insulating film. The resultant precipitated Al nucleus 127 isthen utilized as a seed layer for the liquid phase growth of Al, the Alfilm 128 thus precipitated being filled in the contact hole 154 and thewiring groove 155 (FIG. 42D).

Then, the Sn layer, the Al—Sn layer and Al layer which are segregatedoutside of the contact hole and the wiring groove are removed, thereby.forming a plug and a wiring 128, both formed mainly of Al, only in thecontact hole and wiring groove, respectively (FIG. 42E).

From the equilibrium composition is allowed to precipitate in the liquidphase alloy. By allowing Al to be precipitated from the surface of theinsulating film or from the contact hole, the formation of the plug canbe achieved.

A film rich in Sn component in the Sn—Al film may be employed in placeof the Sn film to be employed at the beginning. Other kinds of filmwhich can be turned into a liquid phase at a suitable processtemperature can be also employed.

The precipitation of Al may be performed by cooling the liquid phaseduring or after the precipitation process of Al from the liquid phase Snfilm or from the liquid phase Al—Sn film, which is performed whilefeeding Al. Further, this precipitation method of Al through cooling maybe performed by cooling step-wise the liquid phase while feeding Al.

EXAMPLE 38

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 43A to43E.

First of all, a first wiring layer 132 is formed on a substrate (notshown) provided with an element. Then, an interlayer insulating film 133is formed over the first wiring layer 132.

Then, the interlayer insulating film 133 is selectively etched by makinguse of photolithography and the RIE to form a contact hole 134 and awiring groove 135 (FIG. 43A).

Then, a native oxide film formed on the upper surface of the firstwiring layer 132 which has been exposed on the bottom of the contacthole 134 is removed by means of a surface treatment. Then, an Sn film136 is filled in the contact hole 134 and in the wiring groove 135 (FIG.43B).

The Sn deposited outside the contact hole 134 and the wiring groove 135is removed by means of the RIE, CDE or CMP (FIG. 43C).

After the native oxide film deposited on the surface of the Sn film 136is removed, an Al film 137 is deposited by means of sputtering withoutbreaking vacuum. The removal of the native oxide film on the Sn film 136can be performed by means of a reverse sputtering, or by exposing thenative oxide film to a flow of reductive gas such as H₂ or SiH₄ whileheating the substrate.

If a native oxide film is existed at the Sn/Al interface, the diffusionof Al into the Sn liquid phase may be obstructed. Further, if a nativeoxide film is existed at the Sn/Al interface, a void may be caused togenerate at the interface between a solid phase Al film and the Sn filmwhen the volume of the Sn film is changed as it is turned into a liquidphase. For the purpose of avoiding this phenomenon, the removal of thenative oxide film is required at the occasion of depositing an Al filmon the Sn film.

When the substrate is heated up to a temperature which enables the Snfilm to turn into a liquid phase, e.g. 450 ° C., the Al diffuses intothe liquid phase Sn film and at the same time Sn is caused to diffuseinto the Al film disposed on the Sn film, thus forming an Al—Sn liquidphase in the contact hole 134 and the wiring groove 135 (FIG. 43D).

Then, the Sn film, Al film and the Al—Sn layer and Al layer which aresegregated outside of the contact hole 134 and the wiring groove 135 areremoved by means of the RIE etch-back or CMP, thereby forming a plug anda wiring 138 (FIG. 43E).

It is also possible as shown in FIGS. 44A to 44E to fill the contacthole and the wiring groove with Sn and then to feed Al by sputtering Alwhile heating the substrate and maintaining the liquid phase of Sn 139.

Subsequently, the temperature of the chamber may be cooled, therebyperforming the precipitation of Al in the contact hole and the wiringgroove. The precipitation of Al may be performed by cooling the liquidphase during or after the precipitation process of Al from the liquidphase Sn film or from the liquid phase Al—Sn film, which is performedwhile feeding Al. Further, this precipitation method of Al throughcooling may be performed by cooling step-wise the liquid phase whilefeeding Al.

Although the contact hole and the wiring groove are filled with Sn inthe above explanation of this example, an Sn—Al film may be substitutedfor the Sn.

EXAMPLE 39

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 45A to45E.

First of all, a first wiring layer 142 is formed on a Si substrate 141provided with an element (not shown). Then, an interlayer insulatingfilm 143 is formed over the first wiring layer 142.

Then, the interlayer insulating film 143 is selectively etched by makinguse of photolithography. and the RIE to form a contact hole connectingwith the first wiring layer 142 and a wiring groove.

Then, a native oxide film formed on the upper surface of the firstwiring layer 142 which has been exposed on the bottom of the contacthole is removed by means of a surface treatment such as a reversesputtering. Then, an alloy film 144 consisting of Al—Snx (x=81.6 at %for instance) is filled in the contact hole and in the wiring groove(FIG. 45A).

The Sn deposited outside the contact hole and the wiring groove isremoved by means of the RIE, CDE or CMP (FIG. 45B).

After the native oxide film deposited on the surface of the Al—Sneutectic alloy film is removed, the substrate is heated up to atemperature which enables the Al—Sn eutectic alloy film to turn into aliquid phase, e.g. 450° C., the temperature is decreased therebyallowing the Al 145 to precipitate in the contact hole and the wiringgroove. Then, an Al film 146 is deposited by means of sputtering (FIG.45C).

When this laminate film is heated to a temperature (450° C. forinstance) which is lower than the temperature which has previouslypermitted Al to be precipitated from the liquid phase of Al—Sn film, theAl in the upper Al film is caused to diffuse into the liquid phaseSn—Al. As a result, a portion of Al which has been excluded from theequilibrium concentration at 400° C. due to a feeding of Al to theliquid phase Sn—Al (which has been previously filled in the contact holeand wiring groove) is caused to precipitate on the Al layer 145 that hasbeen precipitated in advance in the contact hole and wiring groove. As aresult, the contact hole and wiring groove is filled with theprecipitated Al film 145 (FIG. 45D). The Al may be fed by means ofsputtering while maintaining the Sn—Al alloy in a liquid phase in thecontact hole and wiring groove.

The precipitation of Al may be performed by cooling the liquid phaseduring or after the precipitation process of Al from the liquid phase Snfilm or from the liquid phase Al—Sn film, which is performed whilefeeding Al. Further, this precipitation method of Al through cooling maybe performed by cooling step-wise the liquid phase while feeding Al.

Then, the precipitated Sn film and the conductive Al film which aresegregated outside of the contact hole and the wiring groove are removedby means of the RIE etch-back or CMP, thereby forming a plug and awiring 145 (FIG. 45E).

According to this invention, since an amount of Sn expelled from thecontact hole and the wiring groove can be decreased, an amount of Sncompound to be finally removed can be decreased. Accordingly, thematerial remained outside the contact hole and the wiring groove can beeasily removed.

EXAMPLE 40

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 40A to40E.

By means of various methods, at least interiors of the contact hole andthe wiring groove are filled with a liquid phase alloy 106 consisting ofan Al—Sn alloy (FIG. 40B). Then, under the condition which enables asufficient etching ratio to be achieved between Al and Sn, the surfaceof the Al—Sn film is exposed under a heated condition to a gas flowcontaining Cl₂ gas, or to the plasma of radical of Cl₂ gas thereby toremove only Sn. Through this process, the concentration of Sn in thefused AlSn alloy is decreased, thereby producing a change in equilibriumconcentration and hence causing Al to precipitate. This method may becombined with the process of lowering the temperature of the liquidphase, thereby removing the Sn in the form of chlorides, thusconcentrating the Al—Sn liquid phase alloy.

Thereafter, in the same manner as mentioned above, the superfluous Snfilm and Al—Sn alloy which are deposited outside of the contact hole andthe wiring groove are removed, thereby forming an Al precipitation filmin the contact hole and the wiring groove.

In this case, when the native oxide on the Al—Sn film is removed byheat-treating it in a hydrogen atmosphere or in a reductive atmosphere,or by subjecting it to a sputtering before exposing it to the Cl₂ flow,the Al—Sn film can be more effectively removed.

EXAMPLE 41

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 46A to46G.

First of all, a first wiring layer 152 is formed on a Si substrate 151provided with an element (not shown). Then, an interlayer insulatingfilm 153 is formed over the first wiring layer 152.

After a TiN film 159 is formed on the interlayer insulating film 153,the interlayer insulating film 153 is selectively etched by making useof photolithography and the RIE to form a contact hole 154 connectingwith the first wiring layer 152 and a wiring groove 155 (FIG. 46A).

Then, a native oxide film formed on the upper surface of the firstwiring layer 152 which has been exposed on the bottom of the contacthole 154 is removed by means of a surface treatment such as a reversesputtering. Then, an Sn film 156 is filled in the contact hole 154 andin the wiring groove 155. The Sn deposited outside the contact hole andthe wiring groove is removed by means of the RIE, CDE or CMP (FIG. 46B).

After the native oxide film deposited on the surface of the Sn film isremoved, an Al film 157 which is free from impurities is depositedthereon without breaking vacuum (FIG. 46C). Then, the substrate isheated up to a temperature which enables the Sn film to turn into aliquid phase, e.g. 450° C., thereby allowing the Al to diffuse into theliquid phase Sn film, and at the same time, allowing Sn to diffuse intothe Al film disposed thereover, thus filling the contact hole 154 andthe wiring groove 155 with an Al layer 158 (FIG. 46D).

Then, the segregated Sn film and the conductive Al film which aresegregated outside of the contact hole 154 and the wiring groove 155 areremoved by means of the RIE etch-back or CMP (FIG. 46E).

Then, a Cu film 160 a is deposited all over the substrate andheat-treated for 30 minutes at a temperature of 300° C, for instance,thereby adding Cu into the Al wiring (FIG. 45F). Then, the Cu film andTiN film deposited outside of the contact hole 154 and the wiring groove155 are removed by means of the RIE etch-back or CMP, thereby forming aconnector plug and groove wiring 160 b (FIG. 46G).

The Cu added to the Al film is an additive element for improving theelectromigration resistance as well as the stress migration resistance.Accordingly, Cu is generally added in advance to the Al wiring in theLSI. However, Cu reacts with Sn to form a stable compound. Therefore,when a liquid phase Sn is kept in the contact hole and wiring groove,and at the same time, Al is allowed to diffuse into the liquid phase Snwhereby to cause the Al to precipitate in the contact hole and wiringgroove, Cu which has been included in the Cu-containing film employedfor feeding Al reacts with Sn in the precipitated Al. As a result, thetwo-layer separation between Al and Sn may become difficult, resultingin the formation of a highly resistive film containing a large amount ofSn.

Therefore, the Al to be fed employed in this example is free fromimpurities, and after Al is allowed to precipitate from the liquid phaseAl—Sn film into the contact hole and wiring groove, the addition of Cuinto the wiring is performed so as to improve the reliability of thewiring. Therefore, it is possible to form a connector plug and groovewiring which are low in resistance and excellent in reliability.

EXAMPLE 42

In the above example, the contact hole and wiring groove are initiallyfilled with an Al—Sn film or an Sn film by making use of only thesputtering method, and then these films are heated to obtain a liquidphase thereof. However, according to this example, the aforementionedliquid phase filling step is performed in a different manner wherein theheat treatment under pressure is performed while applying a uniaxialstress.

An example of applying a uniaxial stress will be explained below withreference to FIGS. 47A to 47C.

After a lower structure of element and a lower wiring are formed on anSi substrate 161, an insulating films 162 a and 162 b are formed on bothsurfaces thereof. A contact hole and a wiring groove are formed on oneinsulating film 162 a. The reason for forming an insulating film on thebottom surface of the Si substrate 161 is to prevent the Sn fromdiffusing toward the substrate side in a subsequent step. Therefore,other kind of film can be employed as far as it is capable offunctioning as a barrier film.

Then, as shown in FIG. 47A, the substrate 161 is mounted on a wafertable 165 in such a manner that the substrate 161 is immersed in a fusedAl—Sn alloy or an Sn bath 163 placed in a crucible 164. In FIG. 47A, thenumber 166 denotes a heater. Then, the Si substrate 161 is taken up fromthe bath 163 and mounted on a wafer table 167 provided with a heatingmeans and a cooling means as shown in FIG. 47B. At this moment, an Al—Snalloy film 168 is formed on the insulating film 162 a of the substrate161. A heater 170 provided with a susceptor 169 having the same diameteras that of the substrate 161 and made of quartz is disposed to face theAl—Sn alloy film 168 of the substrate 161.

Then, as shown in FIG. 47C, the heater 170 is moved downward so as toclosely press-contact with the substrate 161 and then heaters on bothsides of the substrate, i.e. a heater 170 and a heater of the wafertable 167, or only the heater 170 is heated so as to obtain a fusedAl—Sn alloy or a fused Sn. Due to this, Al—Sn alloy or Sn can be filledin the contact hole and the wiring groove with excellent fillingefficiency. Thereafter, the upper and lower heaters or only the heaterof the wafer table 167 is cooled to allow Al to precipitate.

Subsequently, the heater of the wafer table 167 is cooled to form aeutectic Al plug, and then the Al—Sn alloy film or the Sn film depositedoutside the contact hole and wiring groove is removed in the same manneras mentioned above by making use of a gas flow containing Cl₂ gas, theRIE or CDE etch-back method, or the CMP. The barrier film formed on thebottom surface of the substrate is removed by abrasion or by a wetetching after the step of forming the wiring or in the subsequent steps.

EXAMPLE 43

A method of liquid phase filling by means of a uniaxial stress will beexplained below with reference to FIGS. 48A to 48D.

As shown in FIG. 48A, an apparatus comprising a chamber 174 providedwith an exhauster 173 and housing a crucible 176 filled with an Al—Snalloy or an Sn bath 175 has been employed. The holding of a wafer isperformed by a wafer supporting plate 177 and by a cooling mechanism 178which is adapted to cool the bottom surface of substrate. Through thismechanism, the substrate is allowed to be move upward or downward, or tobe placed into or taken out of the crucible 176.

First of all, an Si substrate 171 is introduced into this apparatus, andmounted on the wafer supporting plate 177. The Si substrate 171 isprocessed in advance so that it is formed with a lower structure ofelement and a lower wiring, and also with an insulating films 172 a and172 b, a contact hole and a wiring groove being formed on the insulatingfilm 172 a. The reason for forming an insulating film on the bottomsurface of the Si substrate 171 is to prevent the Sn from diffusingtoward the substrate side in a subsequent step. Therefore, other kind offilm can be employed as far as it is capable of functioning as a barrierfilm.

After the chamber 174 is sufficiently evacuated, the wafer supportingplate 177 and the cooling mechanism 178 are moved down into the crucible176 filled with an Al—Sn alloy or an Sn bath 175, thereby entirelydipping the contact hole and wiring groove in the Sn bath 175. Underthis condition, an inert gas Ar or N₂ is introduced into the chamber 174and the inner atmosphere of the chamber 174 is pressurized higher thanthe air atmosphere, thereby applying a uniaxial stress on the surface ofthe bath 175 as shown in FIG. 48B.

As a result, even a fine pattern can be filled with the fused Al—Snalloy or Sn. Under this pressurized condition, the substrate 171 isgradually pulled up during which the substrate 171 is cooled by thecooling mechanism 178. As a result, the contact hole and the wiringgroove are filled with an precipitated Al film 179.

Thereafter, the Al—Sn alloy film or the Sn film deposited outside thecontact hole and wiring groove is removed in the same manner asexplained in the above example by making use of a gas flow containingCl₂ gas, the RIE or CDE etch-back method, or the CMP. The barrier filmformed on the bottom surface of the substrate is removed by abrasion orby a wet etching after the step of forming the wiring or in thesubsequent steps.

According to this method, the liquid phase of Al—Sn film can be held inthe contact hole and wiring groove in a more stable manner at theheating step as compared with the method where the filling of the Al—Snfilm is performed by means of sputtering. As a result, the contact holeand the wiring groove can be suitably filled with an precipitated Alfilm 179.

The procedures of Examples 43 and 44 which are illustrated in FIGS. 47Ato 47D are not confined to the embodiment illustrated above, but may becombined with other methods. For example, after Sn is filled accordingto the method shown in FIG. 16, the Al which has been deposited in thequartz susceptor 169 shown FIG. 47B may be contacted with the Sn whichhas been filled in the contact hole and wiring groove, and then theapplication of stress and heating can be performed thereby to allow theAl to precipitate.

EXAMPLE 44

In addition to the methods illustrated in Examples 43 and 44 forapplying a uniaxial stress, the method for stably filling the Al—Snalloy in a fine contact hole and wiring groove in the process ofdepositing the Al—Sn alloy or in the process of depositing the Al—Snalloy film, followed by a heat treatment may be performed by takingadvantage of the capillary action and capillary electrical phenomenon ofthe fine contact hole. These methods will be explained below.

After a lower wiring was formed on an Si substrate, an interlayerinsulating film was formed all over the upper surface of the substrate.Then, a contact hole and a wiring groove were formed in the interlayerinsulating film. Then, in the same manner as illustrated in the aboveexample, an Al—Sn alloy was deposited on the Si substrate so as to fillit down to the bottom of the contact hole. Then, the substrate washeated until a liquid phase was formed. As a result, it was foundpossible to fill and retain the Al—Sn alloy in the contact hole andwiring groove through a capillary action. When the substrate was cooledunder this condition and then held at a constant temperature, theprecipitation of a plug mainly consisting of Al was recognized.

Then, an ion shower or a low energy electron was applied to thissubstrate in the heating process, and at the same time, a bias wasapplied to the substrate, thereby increasing the SN²⁺ in the Al—Snalloy. The substrate was kept in this state for a while during which thesubstrate was insulated entirely from the apparatus. As a result, thesurface energy of the Al—Sn alloy was decreased and the fine contacthole was filled uniformly and stably with the Al—Sn alloy withoutgenerating void, thus making it possible to effectively form an Alprecipitation plug from this liquid phase.

As an alternative method, an Al—Sn alloy was deposited on the Sisubstrate so as to fill it down to the bottom of the contact hole. Then,the substrate was held in a strong magnetic field while electricallyinsulating the substrate, thereby allowing an eddy current to generateand at the same time allowing the electric charge to be temporarily heldby the surface of the substrate. As a result, almost the same effects asmentioned were obtained.

EXAMPLE 45

A method of modifying the surface of an oxide film for forming apattern, which is useful for improving the wettability of a liquid phasemetal or a liquid phase alloy will be explained with reference to thesame FIGS. 49A to 49C.

As shown in FIG. 49A, a lower wiring layer 182 and an oxide film 183 areformed on a substrate 181 provided with a contact hole 184 and with awiring groove 185, and then one or more kinds of inert gas ion selectedfrom Ar, He, Ne and Xe ions are implanted all over the surface of thesubstrate 181 by means of a low accelerated ion implantation method(FIG. 49B). This ion implantation is performed in a manner to enable theions to reach to the surface of the oxide film 183 and to the inner wallof the contact hole 184. For example, when the contact hole is 10 inaspect ratio and 0.1 μm in inner diameter, the ions can be introducedwith a tilt angle of θ=tan−1 (0.1), thereby to enable a sufficientamount of ions to reach to the inner wall of the contact hole 184. Itwould be more effective if the incident energy is set to a sufficientlylow level to ensure the Rp of the ions would become 1 to 2 nm on thesurface of the oxide film 183.

By cutting the Si—O bond of the surface of the oxide film in thismanner, the surface will be conditioned such that an interface reactionwould be easily taken place between the surface of the oxide film withthe liquid phase of the Sn film or Al—Sn alloy.

As a result, a surface modified layer having a good wettability with Snor Al—Sn alloy is formed.

Under this condition, an Al—Sn alloy is deposited by means ofsputtering, and then the substrate is heated to obtain a liquid phase ofthe Al—Sn alloy. Alternatively, an Al—Sn alloy is deposited by means ofsputtering while the substrate is heated to obtain the liquid phaselikewise. At this moment, a surface reaction layer 186 is formed at theinterface between the oxide film and the Al—Sn alloy. As a result, theliquid phase of the Al—Sn alloy or a simple Sn film 187 can be filleddown into the bottom of the contact hole by taking advantage of theexcellent wettability thereof with this surface reaction layer 186.

EXAMPLE 46

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 50A to50C.

After a lower Al wiring layer 192 is formed on a substrate 191, a Ti/TiNlaminate films 192 b and 192 c are deposited as a barrier metal and thenan SiO₂ film 193 is deposited as an interlayer insulating film. Then,the surface of the interlayer insulating film 193 is subjected to atreatment by making use of a low accelerated ion implantation employinga gas mainly consisting of Cl₂, a reverse sputtering or the RIE (FIG.50A). As a result, the entire surface of the interlayer insulating film193 is terminated with chlorine or adsorbed with chlorine (FIG. 50B).

Subsequently, the interlayer insulating film 193 is selectively etchedby making use of photolithography and etching to form a contact hole 194and a wiring groove 195 (FIG. 50C).

Then, the contact hole 194 and the wiring groove 195 are filled with anSn film or an Al—Sn film. Since the surface of the interlayer insulatingfilm 193 is already conditioned to allow a formation of an Sn chloridehaving a high vapor pressure, thus hardly permitting the adsorption ofSn or Al—Sn alloy, the Sn and Al—Sn are now allowed to preferentiallyenter into the contact hole 194 and the wiring groove 195. As a result,the contact hole and the wiring groove can be effectively filled withthe Sn film or Al—Sn film at the occasion of the deposition of the Snfilm or Al—Sn film, or at the occasion of forming the liquid phasethereof through heating.

EXAMPLE 47

In the step of filling the contact hole and the wiring groove with anAl—Sn film or an Sn film, or in the step of precipitating Al throughheating and maintaining a constant temperature of an Al—Sn alloy in theabove example, it is preferable to make a structure wherein a materialwhich is excellent in wettability to the Al—Sn film or an Sn film isexposed at the bottom of the contact hole for the purpose of stablyretaining an Al—Sn alloy in the contact hole and the wiring groove. Itwould be possible with such a structure to effectively form a liquidphase of the Al—Sn alloy in the contact hole and the wiring groove, thusmaking it possible to obtain ultimately an Al precipitation film whichis excellent in buried structure.

Therefore, the contact hole should be formed in such a manner that asilicide film is exposed over an lower wiring or over a pn junction, orthat the surface of barrier metal of an lower wiring or the surface ofreflection-preventing film for lithography is exposed. Alternatively, abarrier metal or an underlying film excellent in wettability may formedin the contact hole and the wiring groove after these contact hole andwiring groove are formed.

A film useful in this case is a film which is higher in surface energythan that of an SiO₂ film (surface energy: 605 erg/cm²), e.g. a Ta film(surface energy: 2130 erg/cm²), an Ni62-Nb38 film (surface energy: 1326erg/cm²) or a Ta-60 at % Al film (surface energy: 1640 erg/cm²) in thecase of amorphous film. A nitride, carbide or silicide, such as TiN,TiC, TiB, TiB₂, TiSi₂, ZrN, ZrC and ZrSi₂ are high in surface energy, sothat these materials are also useful. In the case of groove wiring,these films should preferably be deposited only on the bottom thereof bymeans of anisotropic sputtering. In the case of the contact hole havinga large inner diameter or the groove wiring having a large width, thesefilms may be formed at least partially in the contact hole or in thegroove.

As for the underlying layer which is capable of generating a nucleus ofAl precipitation, a film which is capable of forming VC, TiC, TiB₂,AlB₂, ZrC, NbC and W₂C is useful.

These films can be produced by means of sputtering employing a targetcontaining these elements. As for the carbide and boride, they may beformed by a process wherein Vi, Ti, Al, Zr, Nb or W is deposited atfirst, after a contact hole is formed therein, an ion implantation of Cor B is performed, and then annealing is performed to modify thesurface, thus obtaining a carbide film or a boride film.

In the foregoing explanation, a film consisting of a compound isillustrated. However it is also possible to employ a film consisting asingle element.

EXAMPLE 48

The step of precipitating Al will be explained with reference to FIG.51.

In the case of Example 35, the liquid phase of Al—Sn alloy is obtainedat a point (a) in FIG. 51, which exceeds a temperature of 420° C., thenthe temperature thereof is decreased down to a point (b) of two-phase(solid/liquid phase) region, for example 350° C., and after maintainingthe temperature at this point, the temperature is finally decreased downto a point just over the eutectic temperature thereof.

However, it is also possible to obtain an excellent precipitation of Aland an excellent filling property even in a process wherein thetemperature decreased down to the point (b) which is higher than 228° C.and is just over the eutectic line in one time, and after maintainingthe temperature at this point, the temperature is decreased to the point(c) to finally obtain a solid phase.

In the step of precipitating Al, the equilibrium concentration in liquidphase is caused to change through a decrease of temperature or through aselective etching of Sn, and a portion of Al corresponding to thedifference between these equilibrium concentrations is caused toprecipitate. The following Table 1 shows the equilibrium concentrationsof Al and Sn in each temperature. This phenomenon is also applicable toother kinds of material. The following Table 2 shows the equilibriumconcentrations of Cu and Bi in each temperature.

TABLE 1 Liquid phase temp. and comp. in A1—Sn eutectic alloy Al Sn 300°C. 3.2 96.8 (at %) 350° C. 7.6 92.4 (at %) 400° C. 12.0 88.0 (at %) 450°C. 18.6 81.2 (at %)

TABLE 2 Liquid phase temp. and comp. in Cu—Bi eutectic alloy Cu Bi 300°C. 0.8 99.2 (at %) 400° C. 2.0 98.0 (at %) 450° C. 2.9 97.1 (at %)

In the step of decreasing the temperature down to a temperature which islower than the eutectic temperature, the step of maintaining thetemperature at a constant point after a decrease of temperature is notconfined to once but the step may be repeated twice or more. Further,the step of temperature decrease and the step of maintaining temperaturemay not necessarily be performed in the relationship of 1:1, but thetemperature may be gradually decreased.

Even if the cycle of “temperature decrease/maintaining of temperature totemperature increase (solid/liquid two-phase co-existing region) totemperature decrease/maintaining” is repeated a plural times in the stepof increasing the temperature up to a temperature which was higher thanthe eutectic temperature, it was possible to obtain an excellent fillingproperty. Furthermore, when the temperature decreasing rate in the stepof decreasing the temperature down to a point (d) in the solid/liquidtwo-phase co-existing region is defined as R1, and the temperaturedecreasing rate from the point (d) to the point (b) is defined as R2,even if the relationship between R1 and R2 was in the condition ofR1>>R2 or in the condition of R1−R2, an excellent filling property ofAl, i.e. free from void and uniform in thickness, was obtained.

EXAMPLE 49

Specific examples related to the deposition and heating steps of anAl—Sn film or an Sn film in the above example will be explained inreference to FIGS. 52A and 52B.

Reference to FIG. 52A, an Si substrate 201 is mounted on aheating/cooling means 202, and an infra-red lamp 203 is disposed overthe Si substrate 201.

At the occasion of initially depositing an Al—Sn alloy or an Sn on thecontact hole and the wiring groove which are formed on the Si substrate201, a descending temperature gradient, i.e. at first from the bottomside of the contact hole to the upper surface side is caused to begenerated. Namely, the sputtering of the Al—Sn alloy or the Sn isperformed while directly heating the bottom of the substrate 201 bymaking use of the heating/cooling means 202. In this case, thedeposition is performed by heating the substrate 201 at the temperatureor more which enables a liquid phase to be obtained with the filmcomposition being sputtered (283° C. or more in the case of the Snfilm), and at the same time, by controlling the deposition rate whichmeets the condition of a<b (wherein “a” is a film thickness of liquidphase metal which has been deposited in the contact hole. and in thewiring groove; and “b” is a film thickness of liquid phase metal whichhas been deposited on the side wall of the contact hole) (FIG. 52B).

After the filling of the Al—Sn alloy and Sn is finished, the cooling ofthe bottom of the substrate 201 to a temperature which is higher than228° C. and is just over the eutectic line is performed by making use ofthe heating/cooling means 202, while heating the upper surface of thesubstrate 201 up to a temperature which is not less than the liquidphase temperature. Namely, the precipitation of Al in the contact holeis performed under a condition wherein the temperature gradient isopposite to the initial stage of metal deposition.

With respect to the means for generating the temperature gradient, thesubstrate is heated directly from the bottom of the substrate 201 bymaking use of the heating/cooling means 202 at the occasion of initiallydepositing an Al—Sn alloy or an Sn.

However, the substrate may be heated as follows. Namely, an electrodepad is taken out from the Al wiring of lower layer and the substrate ismounted on susceptor which is capable of directly conducting current orheat. Under this condition, the Al of lower layer is utilized as aheating element, thus heating the bottom of the substrate and generatinga desired temperature gradient.

Alternatively, as shown in FIG. 52B, the substrate may be irradiatedwith an infra-red lamp 203 from the surface thereof. In this case, sinceSiO₂ permit infra-red ray to pass therethrough and the absorption ofheat is effected only by the wiring disposed directly below the lamp,the Al wiring of the lower layer can be functioned as a heating element,thus selectively increasing the temperature of the opening of thecontact hole and hence promoting the filling. The heating of substrateat the step of precipitating Al may be also performed by making use ofthe infra-red lamp, i.e. the upper deposition film is heated with theinfra-red lamp, thus raising the temperature of the upper surface side.

These heating steps may be effectively performed in a high vacuumchamber, or in a reductive atmosphere containing SiH₄, SiH₂ or hydrogen.Moreover, the step of forming a film and the step of heat treatment maybe conducted continuously, the transfer of the substrate being performedwithout breaking vacuum.

EXAMPLE 50

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 40A to40E.

First of all, a first wiring layer 102 is formed on a Si substrate 101provided with an element (not shown). Then, an interlayer insulatingfilm 103 is formed over the first wiring layer 102.

Then, the interlayer insulating film 103 is selectively etched by makinguse of photolithography and the RIE to form a contact hole 104connecting with the first wiring layer 102 and a wiring groove 105 (FIG.40A).

Then, a native oxide film formed on the upper surface of the firstwiring layer 102 which has been exposed on the bottom of the contacthole 104 is removed by means of a surface treatment such as a reversesputtering. Then, the contact hole 104 and the wiring groove are filledwith a Cu—Bi by means of a directional sputtering such as thecollimation sputtering or a low pressure-long distance sputtering. Inthis case, the substrate may be heated to fluidize the Cu—Bi thereby tointroducing them into the contact hole and the wiring groove.Alternatively, they may be filled in the of liquid phase or by thecombination of liquid phase and pressure as illustrated hereinabove(FIG. 40B).

Then, the substrate is heated to obtain the liquid phase of the Cu—Bdeposited in advance. Then, this liquid phase Cu—Bi alloy is cooled downto the solid liquid two-phase region, or the Bi is selectively removedthereby to shift the equilibrium concentration thereof. As a result, anexcessive amount of Al film is allowed to exude from the equilibriumconcentration and hence to be precipitated on the insulating film, thusforming a precipitated Cu film in the contact hole and wiring groove.This precipitated Cu film includes Bi the quantity of which is notlarger than the maximum concentration where the Bi of liquid phase canbe equilibrated with the Cu to be precipitated due to the formation ofliquid phase of Cu—Bi film in the contact hole and wiring groove.Therefore, this precipitated Cu film is mainly consisted of Cu.

Then, the Bi film, Bi—Cu alloy and Cu film which are segregated outsideof the contact hole 104 and the wiring groove 105 are removed by meansof the RIE etch-back or CMP, thus forming a connector plug and groovewiring.

EXAMPLE 51

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to FIGS. 53A to 53D.

The contact hole and the wiring groove are filled with a fused metalfilm 213 consisting of W—Bi by means of various methods explained above,thereby. precipitating a thin W film 214 in the contact hole and thewiring groove (FIG. 53A).

Then, a superfluous portion of Bi is removed by means of the RIEemploying a chlorine-containing gas, and a W film 214 is allowed toexpose. Then, the substrate is set in a chamber provided with gas inletports of N₂ and NH₃, in which the surface of the W film is nitridedthrough annealing, by means of plasma, by using a high pressure, orthrough annealing accompanied in advance by an ion implantation, therebyforming WNx film 215 (FIG. 53B).

Then, the contact hole and the wiring groove are filled again with afused metal film 216 consisting of Cu—Bi, thereby precipitating a Cufilm 216 b, thereby forming a precipitated Cu plug covered with WNxbarrier metal film 215 (FIG. 53C).

Then, the superfluous portions of Cu—Bi, Bi and Cu film which aresegregated outside of the contact hole and the wiring groove are removedas mentioned in the previous examples by means of the RIE or CDEetch-back employing Cl₂, Br₂ or F₂, or CMP (FIG. 53D).

EXAMPLE 52

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to the same FIGS. 53A to53D as employed in Example 51.

The contact hole and the wiring groove are slightly covered with a fusedmetal film 213 consisting of W—Ge by means of various methods explainedabove, thereby precipitating a thin W film 214 in the contact hole andthe wiring groove (FIG. 53A).

Then, a Ge-containing W film 214 or a Ge/W laminate film is allowed toexpose in the same manner as explained in the previous example. Then,the substrate is set in a chamber provided with gas inlet ports of N₂and NH₃, in which the surface of the W film 214 is nitrided throughannealing, by means of plasma, by using a high pressure, or throughannealing accompanied in advance by an N₂ ion implantation therebyforming WN film or W—Ge—N film 215 (FIG. 53B).

Then, the contact hole and the wiring groove are filled again with afused metal film 216 consisting of Cu—Bi, thereby precipitating a Cufilm 216 b, thereby forming a precipitated Cu plug covered with WN filmor WGeN barrier metal film 215 (FIG. 53C).

Then, the superfluous portions of Cu—Bi, Bi and Cu film which aresegregated outside of the contact hole and the wiring groove are removedas mentioned in the previous examples by means of the RIE or CDEetch-back employing Cl₂, Br₂ or F₂, or CMP.

EXAMPLE 53

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to FIGS. 54A to 54D.

The contact hole and the wiring groove are filled with a barrier metalsuch as WN or WSiN film 220 by means of the CVD. Then, the contact holeand the wiring groove are filled again with a fused metal film 221consisting of W—Cu—Bi by means of various methods explained above (FIG.54A).

Then, the fused metal film 221 is cooled from the fused conditionthereby precipitating at first W on the WN film 220, and then Cu,thereby forming a WN film or WSiN film 222 as well as a Cu film 223exhibiting an excellent adhesivity.

After this precipitated Cu plug is formed, the superfluous portions ofCu—Bi, Bi and Cu film which are segregated outside of the contact holeand the wiring groove are removed as mentioned in the previous examplesby means of the RIE or CDE etch-back employing Cl₂, Br₂ or F₂, or CMP.

EXAMPLE 54

A process of forming a connector plug and a groove wiring according tothis example will be explained with reference to FIGS. 55A to 55 D.

An Si semiconductor substrate 231 provided with an oxide film 232, agate electrode 233, and an SiN film 233 e having a thickness of 150 nmformed on the side wall of gate electrode 233 are prepared. Then, animpurity diffusion region 234 is formed by means of ion implantation inthe exposed surface portion (or where silicon is exposed) of thesubstrate 231. Then, a B-doped epitaxial Si film 235 is selectivelydeposited by means of the CVD, and then a Ti/TiN film is furtherdeposited, after which a TiSi₂ film 236 is further formed by way of theRTA process.

Subsequently, the residual Si, Ti and TiN are removed by means of theRIE, thus leaving the silicide film and TiN film 237 which are depositedon the diffusion layer. Then, an interlayer insulating film 238 aconsisting of SiO₂/BPSG is deposited to a thickness of 1.2 μm and madeflat by means of CMP, and then a contact hole is formed therein (FIG.55A).

In the same manner as illustrated in the previous example, after anAl—Sn alloy is filled in the contact hole, an Al precipitation plug 239a is formed through a heat treatment. Then, a superfluous portion of theSn layer, Al layer and Al—Sn layer are removed by means of the CMP. Itis preferable in this case to perform a reductive heat treatment in areductive atmosphere after the removal of these Sn layer, Al layer andAl—Sn layer in order to improve a contacting property of the contactportion.

Then, an interlayer insulating film 238 b is deposited to a thickness ofabout 1.0 μm and made flat by means of CMP, and then a groove forfilling a first wiring is formed therein. Thereafter, a Ti/Ti nitridelaminate film 240 a to be functioned as a barrier film is formed in thisgroove, and then exposed to an oxidizing atmosphere to stuffing thesurface of the TiN film, in which a Cu film 260 is deposited to athickness of 0.3 μm by means of sputtering (FIG. 55B).

The surface of substrate is then subjected to a treatment with the CMPthereby to leave the Cu wiring only in the groove, thus removing the Cudeposited on the oxide film. A Ti/Ti nitride laminate film 240 b to befunctioned as a barrier film is formed thereon, and then a superfluousportion of the Ti/Ti nitride laminate film which is deposited on theinsulating film is removed. An interlayer insulating film 238 c is thendeposited thereon. A contact hole is then formed in this interlayerinsulating film 238 c, and an precipitated Al plug 239 b is formed inthe contact hole in the same manner as described above.

Likewise, the formation of an Al precipitation plug throughprecipitation from a fused metal is repeated employing a materialconsisting mainly of Cu as a wiring, and an Al—Sn alloy as a plug (FIG.55C). As a result, the difficulty of assuring the barrier property by abarrier in the contact hole in the formation of a Cu plug has beendissolved by employing an Al plug which can be precipitated from a fusedAl—Sn alloy. At the same time, by constituting the wiring with Cu, theproblems of resistance and reliability which are involved in theformation of wiring has been overcome, thus making it possible to form awiring excellent in reliability through a relatively simple process.

In the foregoing explanation of this example, the Cu wiring issurrounded by a barrier metal. However, the barrier metal can bedispensed with if an insulating film which is capable of preventing thediffusion of Cu is employed.

The combination of materials in the Examples 35 to 54 is not confined tothe binary alloy, but may be ternary or more. In the Examples 35 to 54,the explanation has been made centering on the Al—Sn system. However,this invention is not confined to Al—Sn system. When a material to befilled is Al, a low melting point metal to be used together may beselected from Ga, Hg and Ge other than Sn. When a material to be filledis Cu, Bi can be employed as a low melting point metal. When a materialto be filled is Ag, Tl can be employed as a low melting point metal.When a material to be filled is W, a low melting point metal to be usedtogether may be selected from Hg, Ga, Ge, Bi, Pr and Pu. Further, Ge andSiGe can be substituted for Si. As for the low melting point metal to becombined in this case, the same materials as in the case of Si can beemployed.

In the above examples, the explanation is mainly centered on themanufacture of a connector-plug and groove wiring. However, the wiringmay be formed according to the RIE without employing this invention, andthe resultant wiring may be used in combination with a connector plugwhich has been manufactured according to this invention. The Al filmemployed in Examples 41, 50 to 53 may be substituted by an Al alloyfilm, such as Al—Cu, Al—Si—Cu.

The term of “liquid phase” employed in this specification is notconfined to a fused metal which is to be formed by heating, but includesa state of solid/liquid two-phase coexistence where the precipitation ofconductive film is to be initiated due to a change in equilibriumconcentration. The gist of this invention resides in the solidprecipitation of a conductive film from the condition of liquid phasewhich exceeds sufficiently beyond the liquid phase line whilemaintaining the solid/liquid two-phase coexisting region as well as thecoexistence.

In Examples 35 to 55, liquid phase line, solid phase line, eutecticpoint, crystallizing amount, or the like is shown as a value in theequibrium state at normal pressure. However, the present invention isnot limited to these cases. The present invention can be applied to thecase under the other pressure.

It should be noted that in addition to the combinations set forth in theabove examples, various combinations are possible.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalent.

What is claimed is:
 1. A method of manufacturing semiconductor devicewhich comprises the steps of: forming an insulating film on asemiconductor substrate provided with a conductive layer; forming acontact hole through said insulating film to a depth reaching to saidconductive layer and forming a wiring groove in said insulating film;forming a substitutive film so as to incompletely fill interiors of saidcontact hole and said wiring groove, but at least partially filling saidinterior of contact hole with said substitutive film; forming aconductive film at a region comprising said contact hole and said wiringgroove; forming an absorption layer on said conductive film, and fillingsaid interiors of said contact hole and said wiring groove with saidconductive film by substituting said conductive film for saidsubstitutive film and by allowing said substitutive film to be absorbedby said absorption layer under a heat treatment; and removing a compoundformed in said process of allowing said substitutive film to be absorbedby said absorption layer, and forming a plug comprising said conductivefilm in said contact hole as well as a wiring comprising said conductivefilm in said wiring groove by working said conductive film so as toselectively leave said conductive film in said interiors of said contacthole and said wiring groove.
 2. A method of manufacturing semiconductordevice which comprises the steps of: forming a first insulating film ona semiconductor substrate provided with a conductive layer; forming acontact hole through said first insulating film to a depth reaching tosaid conductive layer; forming a substitutive film in an interior ofcontact hole; forming a second insulating film all over an upper surfaceof the substrate; forming a wiring groove in said second insulating filmin a manner to connect it with said substitutive film; forming aconductive film at a region comprising said contact hole and said wiringgroove; forming an absorption layer on said conductive film, and fillingsaid interiors of said contact hole and said wiring groove with saidconductive film by substituting said conductive film for saidsubstitutive film and by allowing said substitutive film to be absorbedby said absorption layer under a heat treatment; and removing a compoundformed in said process of allowing said substitutive film to be absorbedby said absorption layer, and forming a plug comprising said conductivefilm in said contact hole as well as a wiring comprising said conductivefilm in said wiring groove by working said conductive film so as toselectively leave said conductive film in said interiors of said contacthole and said wiring groove.
 3. A method of manufacturing semiconductordevice which comprises the steps of: forming an insulating film on asemiconductor substrate provided with a conductive layer; forming acontact hole through said insulating film to a depth reaching to saidconductive layer; forming a substitutive film at least in an interior ofthe said contact hole; forming a wiring groove in said insulating film;forming a conductive film at a region comprising said contact hole andsaid wiring groove; forming an absorption layer on said conductive film,and filling said interiors of said contact hole and said wiring groovewith said conductive film by substituting said conductive film for saidsubstitutive film and by allowing said substitutive film to be absorbedby said absorption layer under a heat treatment; and removing a compoundformed in said process of allowing said substitutive film to be absorbedby said absorption layer, and forming a plug comprising said conductivefilm in said contact hole as well as a wiring comprising said conductivefilm in said wiring groove by working said conductive film so as toselectively leave said conductive film in said interiors of said contacthole and said wiring groove.